Becky, you could ask 5 different people and probably get 5 different preferences. With that in mind, here is how I would answer your questions:
I just bought my p-touch but I did want the option of 1" (24mm) so I chose the PT2730.
I am using white on black for named cultivars and black on white for seedlings.
My 14 yr old daughter wanted pink, so we are trying it. It states it is for indoor or outdoor use, so we will see how the pink does. I could only find that in 1/2"(12mm) size so we did 2 lines...2 and a half on this example. She likes color so her eon plates are the colored ones (smaller eon plates purchased in a coop about 4 yrs ago). She likes the shorter smaller markers.
Now me, I like the taller markers, you can always push them down further if you want them shorter.........would love to get Kincaid markers and may slowly switch over as old eons rust out.
I just purchased my tapes from Staples this first time as I wanted to get started right away. It does look like it is cheaper to buy online but I am still looking around. I think I am going to steer clear of the "generic" replacement tapes and stay with the Ptouch brand name tapes unless someone here can vouch for them...
My ramblings may or may not help. All I can do is share what I know to help you make an informed decision. Others will most likely share too.
Good luck.