Shouldn’t have to many problems soloing the objectives and plenty of people on here who I am sure will help, there’s also a OcUK Discord channel, which I should probably get around to looking at. Some may even boost you, I’d be happy to help when I’m on later.
As you say the first set you get given, others you will pickup as you go. My 4 sets I mostly picked up within a week and since have collected more powerful items over time.
Seasons normally last 2-3 months I think.
Also take a look at this;
https://www.icy-veins.com/d3/barbarian-leveling-and-fresh-70-guide-patch-2-6-1-season-12