why not have both form 1 and form 2 open as subforms simultaneously and just change the .visible property of each according to the one you want to see/use.
your joins are inconsistent. you could make them both inner joins (option 1), but this might not return the records you want - your para numbered "1" doesn't make sense to me - pls clarify.
A tricky question. In Acc2000 I've got a combobox control on a continuous subform which refreshes on the OnClick event so that the user can select a value for that row from a small number of choices. Often/usually there is only one choice, so my users have the unentertaining task of clicking on...