For me full suspension means a
Brooks 66 saddle and a Girvin Flex stem 
...
If I was building something along the lines you want to do I would either copy someone elses bike or read up on motorcycle suspension theory ( same concept)of which there is numerous books about. There is a place in California that sells some bits for suspension bike frames,
www.fairing.com . When I last bought from Fairing a few years ago, they would not sell to individuals only a business. Their website has changed since then, so I am not sure what their policy is now.
Tools? from a minimalist perspective.... a selection of files, hacksaw, drill press, good straight edges and measuring tools, access to a welder with tig experince etc.