1. is up to you.. but 2. 5-MeO-MiPT is almost certainly more potent vaped, being a parenteral route (meaning that for a lot of drugs eating them is less efficient).
4-HO-MiPT may be an exception because it may not survive the heating so well, so that one is definitely best eaten or if you must, snorted or plugged etc but not heated above boiling water temp.
3. & 4. Well you waste some from having to learn to vape chems, for example with DMT you almost have to (or you have to eat MAOIs)... whether it's better is up for debate and a matter of taste. For some psychedelics an intense breakthrough flash is very interesting, but it can also make it an anxious white-knuckled ride for some. So depends.
I happen to not like smoking or vaping, other than weed, but I wouldn't say it's not efficient, and DMT is amazing smoked.
4-HO-MiPT is perfect orally, aside from not being the most potent / economical way. Cause you don't really want that one to come up more intensely and anxiously IMO. 4-HO trypts come up quickly anyway so it's not worth it. Also expect it to be disgusting to snort.
I don't like 5-MeO-MiPT but I guess snorting it is not strange, the salt form at least. I've even snorted 5-MeO-DMT fb and that was painful but you can do it. In salt form it dissolves better in water and absorbs better in your nose. Still a bit caustic but the doses are not super high anyway and many psychedelics are caustic to snort.
For me 5-MeO-MiPT is anxiously energetic even orally but many people don't have as big a problem with that. Not sure if you have experience but I'd start out with trying 5-MeO-MiPT orally before doing anything else.
With both the snorted dose will be a bit lower.
Long story short: whether vaping is a good idea depends on the psychedelic. Not all stable enough to do that, and the effects vary and comeup times do as well. So sometimes there is benefit, other times mostly downsides.