That’s wonderful, I’m so happy for you and your new boy! Typing this with my 10th rescue snuggled up to me on the sofa.
if you haven’t already done so, I’d recommend lifetime pet insurance, the highest cover you can get the better. Lifetime means the condition is covered for life with that insurer but, if something is wrong, you’ll struggle to get it covered with a new insurer. Rescues usually start you off with 4-weeks with PetPlan.
I use Many Pets where you only pay one excess a year, no matter how many conditions you claim for - which has saved me a fortune - and they’ve been very good with my last 4 dogs.
Re the gate, it’s worth changing the hinge to a spring one so there’s no risk of it being open if your curious dog gets out accidentally.
Grannick’s Bitter Apple spray is great for deterring furniture biters. I bought the refills and a cheap water spray bottle to save money but have used it for over a dozen dogs over the years with great success.
My final tip is music. I sang to all the dogs I collected from rescue and a friend’s puppy if they started crying or howling en route and, even now, they love those songs. I also leave music playing when I go out so they’re not alone.
You will find some days challenging but kindness and patience will be rewarded. Mine always responded more to cuddles than treats and were also trained to hand signals, as well as words. They just want to please you and be loved.
Beat of luck!