The answers to most of your questions will depend on your climate zone/humid or dry?, etc. If you don't know your zone just tell us the general geographic area where you are gardening. Turns out that roses act differently in different climates - really.

Jackie

I moved mine last year from a north east exposure to a west exposure and she is going gangbusters. Never looked quite so sweet before !!!

try not to prune. my bourbons seem to pout after pruning and i have seen more blooms when i skip pruning

REALLY. I know this is a glorious rose -- SOMEWHERE. NOT where I garden. So, you are where??

Jeri
Coastal Ventura Co, SoCal

This rose is a lovely one for me, I have three of them. It's slow to mature, but worth the wait.

I prune in spring time, but it can bloom well on twiggy wood, so I'm careful to not remove all twiggy growth.

I prune back long canes in spring time, not late summer or autumn.

I deadhead after blooming, to encourage repeat bloom. It does repeat bloom, but can rest a bit in the warmest time of summer.

It appreciates plenty of sun, and seems to thrive on organic fertilizers.

I had a grafted Mme PO and it was one of the best bloomers in my zone 10 garden (coastal Los Angeles). The first 3 years it rusted badly, but I kept it for the exquisite flowers. About year 4, it strengthened and only rusted during seasonal changes. I let mine grow out into an arching shape - it made a slender graceful shrub with arching 7-9ft canes in its prime. There's regular dieback, so I pruned back the dead wood eventually removing the cane when it really started to fail. My grafted shrub lost its vigor after about 9 years, and I started an ownroot one this summer. It's an exquisite rose for both coloring - the flowers blush beautifully - and scent. One of my favorites. My Bourbons must be planted in the sunniest spots to thrive here in the coastal belt, it's just a little too cloudy and cool for most of them.