If you have your necessary passport, immunization, and form that the airline attendants give you to complete to show the officials when you arrive at the airport, then getting a visa then shall be no problem--that is what I did.
The cost of living (ie: food) will be dependant upon your eating style.......one can affordably manage to eat on a maximum of $20 USD per day if you are not one to have to eat lavish meals every day. If you are wanting to eat expensive type meals ( much alcohol, seafood, much beef/chicken) then you will pay somewhat more. Overall the cost of eating is quite reasonable.
Internet fees vary somewhat dependant upon where you are in Nairobi, but usually the cost is about $3-5USD per hour.
If you are staying at a hotel, then you can usually pay the front desk or a room keeper a fee to do your laundry. Don't know the exact cost, but again, quite reasonable.
Hope this helps a bit.