Glad to see you are still with us and didnt get scared away!![]()
To answer your questions..
1) you should easily be able to do water changes without aging. Even here with huge swings between aged and tap water I can still do 25-30% wc unaged.
2)blackwater is not necessary. Clean water is. If you want the look of blackwater its doable with some milled peat moss in your filter..or high tannin leaves. Alternatively you can add rooibos tea.. several here use that.
3)Wetspot has a good reputation for fish in general. As for their Discus, I havent seen many pics posted here by hobbyists. The thing that is important to remember when buying discus.. if you buy them from a local fish store they have been exposed to many things as weekly these places get fish in from all over. Often they are housed with fish that really aren't a great match for discus and often they are kept at temps that are inappropriate for them. If you buy them from a discus seller that specializes in discus you minimize alot of risk associated with petshops.
Im not knocking petshops here but it is the nature of their business and should not be overlooked.. There are also some lfs that do a really good job with a hard situation.