Hi Tony,
There are many members here that own and operate the President McKinley and by all accounts it's a pretty good and fully fledged multi mode/multi band CB radio. It may take you a little while to get used to operating it with all the 'bells & whistles' but the manual is pretty good and there are plenty of YouTube videos on this radio. Worth having a search on the old internet and perhaps some other members who own this radio can give you a few pointers.
As for an antenna, the best one is often whatever one you can put up. (Certainly better than no antenna!
)
If you're running mobile any good mag mount will serve nicely and with a vehicle at least you can drive to high ground to gain an advantage.
(Easiest way to add antenna height.)
For home use a good home base antenna will serve you well and up to you whether that is a half wave, five eighths, etc. The 'bigger' antennas will serve you much better than the cheaper small antenna systems that's for sure.
You'll probably find there are many other caveats or points of view as regards manufacturers, type of coax to use etc. The best advice I can give you is don't skimp out by buying cheap equipment, buy the best you can afford where possible.
I hope that's of help, but do enjoy yourself whilst getting set up and learning to operate your radio.
All the best,
Victor