1) Training/developing a broad range of skills is doable however, depending on the skill level required and your base of existing knowledge, expect that it can potentially take a long of time to build up proficiency.
2) 80-100hr races, I expect will require a lot of time in training in your aerobic zones. This becomes a matter of training time volume. Lots and lots of time spent on your feet, in the trails, at low/moderate intensity levels. Majority of people have FT job and family commitments so you’re not alone however, at the end of the day the training volume that they CAN commit to…will greatly influence their abilities to perform and therefore, so it should inform their expectations on how well they can expect to place in races/events/etc.
So what I’m saying is, if you do not have much time to carve out for event specific training…it’s going to be tough to achieve extremely demanding goals. The training needs to be in alignment with the goal/event…and vice versa.
Incongruent example, “I train 3 hours a week and want to complete the Barkley Marathon”
Congruent example, “I train 20+ hours a week and want to complete the Barkley Marathon”
Here are some links to previous similar discussions, they may provide more details for you:
All the best!