Re: Tools. What is absolutely necessary?
Theres no way to properly answer that but For starters:
A decent socket set and wrench set
hex key set
measuring tape / steel rule
Every tool you learn to use youl find soon enough you cant use to its full potential without another tool. There's almost no end to what you can do with hand tools for general building and fabrication.
Power tools generally make things easier but they are expensive and can be a constant money drain. For example Palm sanders come in every shape and size you can think of usually with pricey replacement sanding pads and limited selections that wear out fast. Sanders designed for good old sandpaper will be far far cheaper to operate. For the price of an electric palm sander you could also get an assortment of different sized and shape hand sander blocks that take standard paper and always have the right tool. Its the same for most power tools there was always a manual way to do it before that power tool was made and usually that's the cheaper way to go.
You may notice that different kits neglect certain sizes of sockets / wrenches 11mm and 18mm is commonly missing for example. You'll notice sizes like 10, 12, and 14 are common but 13mm is less common and 11mm is rarely used. But you will always run into these sizes if you don't have the tools, just the way it works.
local classifieds for used tools is your friend best to just start collecting them all.