imagine 5 indeed , but remember amiga also has such as Lightwave which i recomend over imagine.
anyway for tcp stacks , either Genesis (on your os3.9 cd!) or try and get Miami or miamiDX , sadly thoose are rather impossible to buy or register so either buy it used or go for genesis.
a new tcpstack is out soon enough, its called roadhouse and will be available outside os4 even, so u might keep an eye open in the news sections.
genesis supports broadband ofcourse though i think miamidx is far superior.
beyond that, for a 060 or ppc or other hw , keep an eye open at ebay, normally pops one or two there each month (u can use a normal a4k card so..)
welcome to amiga org and keep thoose questions comming.
cheers