Questions from a newbie ham

Right, so this is the situation: I still haven't obtained my license here in Brazil, but I already have a Baofeng DR-1801 HT that can connect to dmr networks. Therefore I haven't transmitted yet. But I'd like to clarify some doubts:

• When I get my license, even in C-class in Brazil, I will be allowed access to some frequencies in 40-10m bands. Should I get a low power QRP transceiver (e.g. uSDX) or go for an used rig from known brands?
• It's almost impossible to find a transceiver project with a power rating greater than 10w. What would be the difficulty of, say, copylefting the schematics of an ft-7b?
• Can I really use a wire thrown over my house (of course, with baluns and stuff) as a monopole antenna or that's just myth?