1) I have never went up Goreliy (even though Mutnovskiy and Goreliy are right across from each other), but by all accounts it's an easier ascend. Not that Mutnovskiy is that hard, mind you.
Some of my friends who are hard-core snowboarders/climbers/hikers/off-roaders actually prefer Goreliy, even though it's an easier hike. It's also less crowded normally. Don't beleive the fumarolesare as spectacular as on Mutnovskiy, but there's a lake in the crater.
I would recommend some shoes with non-slippery soles, on either volcano you'll come across streams, wet stones and such. Some light gor-tex shoes perhaps.
2) You never can tell, but in the city it should defo be above 20 most of the days in August, but not by much. 19-24 would be an educated guess (daytime). There isn't much difference between daytime and nighttime in the city (maritime climate), but anywhere inland it's more continental, and day/night difference in temps can be significant.
If you have any tours to the east coast (Sea of Okhotsk) - although I doubt it - it's always cold in there. You'd need a fleece and maybe even light jacket even on August day. Can't see why you'd go there though.
Last couple of years it was well above 20 every time I went, it's getting much warmer, probably due to a global climate change, and temps were regularly climbing in lower 30s even. Keep in mind that humidity is 85-100% most of the time, so even 24C feels very hot - you sweat a lot.
That being said, it can be overcast and drizzly and stay 15-18C for a week easily.
Inland Kamchatka has continental climate, so it's way hotter in the summer and way colder in the winter.
Now, when you're up the mountains it's of course colder due to altitude, but last summer on Mutnovskiy I wasn't even wearing a t-shirt and it was plenty warm. It was early August too. That beings said, later in the day clouds and wind came and it became chilly and wet in like half an hour or even less.
It's not really nearly an arctic place, think more like British Columbia, Canada or Scotland - you should be more concerned about staying dry, then staying warm.
Some fleece/wind breaker for sure will be needed, especially on the helicopter. Although on tourist rides I doubt they ever open windows (and definitely not the door).
I don't know why would you need a tent - all heli tours are day tours. If it's some 2 or 3 day tour, I would assume they have adequate equipment, tents, sleeping bags, and such.
3) I've found a couple of tours to Tolbachik, but it's all in Russian - either one day (with taking off as early as 4Am and coming back by midnight) or 2 days with staying over either Anavgai/Esso or Kozyrevsk.
Then the flight for 1-2 hours around the eruption with landing for photo-ops.
Can't find anything in English from a known tour company, but there might be something.
I would prefer a heli tour from the city (well heliports are outside - maybe 45 minute drive on regular roads) seem like a far better option, though more expensive. Don't think with time constraints especially it's worth it. That being said, ask your tour operator once you choose one, maybe they do have a strictly helicopter tour.
People also just drive up there on 4X4s and then just choose some spot to watch the eruption.
But you'd need to stay overnight somewhere close, too long a drive.Volcanologists go up there for sure to take lava probes and what not, but no one will let you do that.
There are also a bunch of hot springs/thermal pools/spas in Paratunka valley.
It's basically hot spring water, cooled down with regular cold water and diverted into pools.
You can take a micro-bus or a cab there. They are different in quality of service, facilities, etc. If you choose a tour operator they might help you with it. I personally like the one called Antarius, but it's really a personal preference.
Keep in mind that popular one called Blue Lagoon has highly chlorinated water. It's mineral real water alright, but too diluted, and the chlorine is just unnecessary, feels like a regular water park. So I would avoid it, even if someone tries to peddle it to you.
Other ones get better or worse depending on owners (especially whether they are willing to invest in business enough money and effort - which is frankly not that common).
Those places are just to soak up hot mineral water for a few hours. There are also open self-made pools in a bunch of places and mud baths as well.
The ones outside Paratunka, are kind of wild places, not much in terms of amenities, but it's more real, just more satisfying in a way to be there.
If you have heart conditions though it's not recommended to stay more than 30-45 mins at a time (water is very heavy with all sorts of minerals). Although most people spend hours (me included) in the pool.
You can look into Malki and Esso tours (places inland with nice climate and those hot springs), but since you don't have much time, I'd defo concentrate on Valley of Geysers/Uzon, Kurilskoye Lake and some volcano (Goreliy/Mutnovskiy or some other) - much, much more interesting.
I believe on Kurilskoye you can also get a boat tour (ask the tour operator). If you can - go for it. Really beautiful and tons of bears all around the lake. Plus a couple of beautiful islands in the middle of the lake.
Not sure, if they do boat thing with tourists all the time, but I've seen some for sure while we were jetting around (I was with park rangers though, not a regular tourist thing at all).
Also if you have down time in the city, you can take a boat tour around Avacha Bay. Shouldn't be that expensive, and IMO worth doing. There are marine animals, birds, you might even spot an Orca (or even a few) if you're lucky. There's also fishing and sea soup, all that good stuff.
Nalychevo park to the north of PK (right behind Avachinskiy/Kozelskiy and Koryakskiy volcanoes) is pretty too, but nothing that special. Wouldn't stay there overnight.
Keep n mind that there are tons of mosquito and little flies that bite you like there's no tomorrow. You can by all sorts of bugs sprays though anywhere - any supermarket or even mini-market. If you have some bugs-away type clothing (Columbia, Zorrel and Ex-Officio make them) - take it with you. No insects in Kamchatka carry any diseases, and while there are ticks, there is no Encephalitis, and I personally don't know anyone at all who has ever got a tick. If you aren't protected against mosquito and flies though - be prepared to get a hell of a scratch all over your body.
You don't need to buy bottled water - all tap water is clean, crispy and actually tastes good. That being said there are several brand of local mineral water (and sodas based on mineral water) and they are all excellent.
Edited: 11:41 pm, June 10, 2013