Thinking about buying a draft cross...need some info

Ok, I finally found a horse I really like. He's an 11 year old red
roan Clyde/QH cross gelding. He's 16.2hh and about 1300lbs and dead,
dead broke. Tons of uneventful trail miles. Sounds perfect for me. I'm
going to try him again later this week. If that goes well, I'll put in
an offer pending favorable PPE.

Now, before I (hopefully) buy this boy, I need to know some of the
logistics regarding such a big horse.

1) I have a flex tree full QH bars trail saddle. Is it reasonable to
think it will fit him or do I need a draft saddle?

2) ditto for the bridle. I have a full browband bridle. Ok for him?

3) My last horse, Jo,  was a big horse as well, so I have a couple of
5.25" bits. Do I need wider ones?

Anything else I need to consider? The place he's going to board at has
show Arabs and the care is first rate. The barn owner and head trainer
have something like 50 years combined experience but they have stock
type horses and Crabett Arabs. Do they need to feed Big Horse anything
different from their lighter horses? Joint suppliments or anything?
I'd rather be prepared beforehand. I've only had an AQHA and an Arab
as well so this boy will be something new to me as well.

Thanks for any info.