Your call entirely but if asked, I'd suggest much lower tire pressures.
I run my 2' tires at 30 psi.
In my opinion anything over 50psi is asking for trouble being hard on rims and spokes, not to mention being hard on your rear.
I find wider tires much more comfy than skinny tires but, like saddles, everyone's opinions different.
I also rarely bother with much more than 50m as much more and I dont feel like getting back into the saddle the next day.
Even after a tour of over three months this was so for me.
I suspect your speed average may increase a little but not by a whole lot.
Dont pay too much heed to your speed and try to keep your cadence in the mid eighties to nineties, which in my opinion, is easier on your knees which quickly show up any straining the bod doesnt like.
I reckon you need to read all the threads in this section like I have for your answers rather than asking for individual answers for all your questions so you develop understanding and reasoning for why different opinions are out there and thus being able to make informed decisions for yourself or at least recognizing where your gut instincts are kicking in.
An Australian site but I believe most of the info will be relative to most countries and the blog is pretty damned inspiring if I say so myself
http://www.cycletrailsaustralia.com/
As others here have said
http://www.crazyguyonabike.com/
and alternate active forum:
http://www.bicycles.net.au/forums/
(especially the touring section)

Oh and congrats on the weight loss and all your hard work!!!!!