First of all, nothing you did with your DS1 made him a fussy eater. Fussy eaters just are. Same as non sleepers, tantrummers and bolters. It's just who they are. There are countless people, I'm sure, who will happily tell you the they have 2 children weaned in exactly the same way resulting in one fussy and one non-fussy child.
Stop beating yourself up and stop over thinking it.
Wean however you feel most comfortable. If you're happiest with purées stick with them and just gradually introduce finger foods and more lumpy stuff as you go along.
If you want to do a more BLW approach then a butty is absolutely fine. You do need to be conscious of the salt content in the bread as one slice normally has their full RDA but as long as they don't have any other salt during that day it's fine. Mine loved toast from day one so "stuff" on toast was always a winner.
I think the majority of people do a bit of both tbh.
I didn't eat tea with him as I don't like eating that early. I just made him whatever was in the fridge/cupboards at the time or I'd make extra of what I planned to have (if it was suitable for him) and re-heat mine later.
I didn't want salt free, non spicy, "healthy food" every single night so we just went with the flow!
A handy staple to have in was a big batch of tomatoey veggy sauce frozen in portions added to a bowl of pasta. Easy to pick up, quick to make, and he loved it. (Won't touch it now of course but he's learnt his toddler prerogative of "no I don't want it" so ends up with beef stew and dumpling 4 nights out of 7 
)
You're doing fine, stop stressing 