Thickness of beadboard for porch ceiling?

What widths are available? 3/4" sound good to me.

What material? T&G or lap or butt-facing joints?

If T&G or lapped, "might could" get by w/ as thin as 3/8" if it's a well-behaving straight-grained sorta' material in a dry area. However, most ceiling beadboards I've seen are 5/8" or 11/16" for some of the original on the house here (1915-18 vintage). I'd probably opt for nearer 1/2" minimums myself, but I really can't see why 1/4" would be of any real concern. Is the concern the weight or the clearance?

T&G pine or maybe cypress to deter the insects.

Both. Weight, because I'll be attempting this pretty much on my own and my previous diy experience is sorely lacking.

Clearance because I'll have to fit around some porch support brackets that are about 1/4" thick and I want to try to make evreything as nearly flush as possible. I've thought of maybe beveling the boards next to these plates/brackets to meet at the same level, but doing something like that may be way beyond my ability. I'll probably end up trying it just to see how it goes, though.

Thanks....