Absolutely nothing Koopa.
The only requirements are really at the Laos side, where you need to fill in two forms, have 1 passport photo, & hand over the dosh.
When returning to Thailand you only need to fill in the entry/departure card. Do not forget to enter the visa number in the space provided & CHECK that they give you 90 days before you leave the Immigration Officer. Oh, I think that on enter Laos & Thailand at the minute you need to fill in a 'swine flu' document as well (nothing too onerous).
do I have to show or register where i'm living?
No, but you do have to fill an address of where you are staying on both the Thai & Laos documentation - but it could be ANYWHERE
show any income or savings
Absolutely not.
take my wife with me
Possibly cheaper if you do not!!! But that may lead to 'personal problems'. Duty free is worth a stroll around & I have yet to encounter a lady from anywhere that did not like shopping

(There are a few places where you can have a coffee or beer while she indulges)
Do not forget if you visit Laos the day (or so) before the visa expires you can get as near as dam it 15 months stay out of that visa..
