Hi Tony,
You have a couple of options:
Option 1:
- Enter one long task "build aquarium" and set the duration to 8 weeks.
- Set the Task Type to Fixed Duration, non-effort driven. (use the Task Form in the lower pane). This will prevent Project from recalculating the task duration when you enter work.
- Then using the task form, assign the 2 days of work for your friend and the one week's worth of work for you.
Project will calculate the assignment units needed to spread the work across the 8 weeks. It will calculate a pretty low percentage spread evenly across the duration. If you are tracking, you can then enter the actual hours as they occur.
Option 2:
Be a bit more detailed. Break the 8 weeks into more discrete pieces. So the first tasks where your friend is helping you for 4 hours -- set that up. Then define the "waiting tasks" as needed and don't assign anyone to them. This will allow the breaks in work and be a bit clearer about when during that 8 weeks your work is required.
Regarding the non-project projects -- I personally wouldn't. The advantage of an 80% allocation is that you are automatically saying that there is 20% in "other work" that you don't need to track or plan as closely as other projects. If you want to use 100% allocations, that is fine as well -- and you can view your "free" time by adding Remaining Availability to the Resource Usage view to see when you can slot in the other work.
I hope this helps.
Julie