I'd be perfectly ok with that. But it doesn't have to be based off a spell list to do that. Without any real reference elsewhere, you can use those abilities. Teleport is a word everyone can understand. Change shape might be a better word than Polymorph. But they don't have to reference spells if they aren't complicated.
Yes, but if you do base it on a spell you can ignore rare issues in the monster entry and still have the rules explain them in the spell entry. If the monster ability uses the teleport spell you know it's an extradimensional ability that is barred by dimensional anchor and only works within one plane, you know how much stuff the moster can carry with it, etc.
However, having a ambiguous description in the monster's description is probably just as bad as having no description. If I want to know if Freedom of Movement can stop Entangle, I'm still going to look up the full description of the spell anyways since "impediments" can mean a lot of things.
You can still either ignore the spell entry and just make a ruling or, if you do care about RAW, look up the details. Most of the time the effect will be obvious, for spells like slow or hold person, if the ability comes into play at all.
Of course, most spells should be simple to summarize accurately, but some complex spells are bound to appear and being able to go into less detail in the moster entry seems like an obvious win to me.