I use True for Intenet, costs very little speed is good and reliability is no issue. You need a phone and adsl connection, you just go to a True shop with your pasport and visa and you'll be right.
I dont know about renting , I own a house in Bangkok. It worked out at around $200k Australian for a gorgeous place in a soi off Sukhumvit road. You need a company to do this, contact Sunbelt Asia and they will help you out.
Edit: In Thailand most things are negotiable, even tea money that the police demand from you when you're riding past a traffic check on your scooter
