We do Disney almost yearly but we usually go in the summer so I can’t speak to other best times to visit but I absolutely would use a planner to book everything. They can offer up advice on when to go when it’s less crowded. The planners are completely free to you (they receive a commission from Disney) so it’s really a win-win to use. Courtney with My Mickey Vacation Travel is outstanding! She visits very often and knows the parks inside and out. She also is a master at booking dining for the group. Can’t recommend enough!
I always prefer to stay at a resort on the monorail or one that you can access Magic Kingdom by boat but Disney makes all the resorts a magical experience. It’s really the best place ever!