I am 50 and really got back into mountain biking about 2 years ago. I went with the Roscoe 8 and my son in law upgraded his Gary Fisher full suspension for a Fuse. The Roscoe is 2.8 inch and the Fuse runs 3 inch. Both are a blast to ride. I agree, the front suspension is great and the plus tires give some cushion. Depending on the types of trails you ride will depend on the need for the full suspension. You might want to rent some bikes or wait for the LBS has demo ride days to get the true feel of the bikes. I have ridden 29’rs and I like the 27.5 better but I am not very talented so I can’t use a bike to it’s fullest. In the end I don’t think you can make a wrong decision with the bikes that are out there especially when you get above the $1500.00 mark.
I use the Garmin Vivoactive HR. Couple years old, great battery, so far no issues other than a broken band. Connects to phone to use Strava, MTB Project, Trail forks and even the GPS in my truck. Plenty of apps to make it useful and very inexpensive. Will even find my phone. When it dies I will definitely purchase another Garmin to replace it.
One of the best ways to find out the maximum tire width is to go to the manufacturer. They will normally give you a size range of tires or alternatives. Another good way to go is the local bike shop. If your local mechanic works on that manufacturers bike they will have knowledge of what tires fit and what are some of the draw backs.
Goals this year are pretty simple. Ride new trails. Each year I take a fishing trip with my son-in-law to northern Wisconsin. This year we will include hitting some bike trails in route and venture to the U.P. to hit a trail. Upgraded the bike this year from an old Diamondback to a new Trek Roscoe 27.5+ so I will attempt to tame the John Muhr trails and possibly try the Emma Carlin also.