Saying "wir sind heiß" means either your temperature is literally high, or that you think you're attractive, and neither of which is the implication here. The expression for feeling of temperatures is always "es ist (adj) noun [Dative case]". 'Es' can be omitted o/c. English makes no such grammatical distinction and it all depends on context.
what about "Wir fühlen heiß"
That makes as little sense as "we touch hot".
When you're talking about how you feel "inside yourself", rather than feeling some external object, you need sich fühlen (reflexive).
But as you guessed, wir fühlen uns heiß would mean "we feel attractive".
It's easy for a plosive to slip in between a nasal sound and a fricative, as in "hamster" being pronounced "hampster", or "strength" as "strenkth".
So "uns" can sound like "unts" sometimes. It's not strictly speaking correct but happens easily when speaking due to the way the sounds come together.
Is "To us it is hot" a legitimate translation of this
No, because one sentences not word-wordly outof one language into the other overset can. (Nein, weil man Sätze nicht wortwörtlich aus einer Sprache in die andere übersetzen kann. = No, because you can't translate sentences literally from one language to another.)
Uns ist heiß means "we are (feeling) hot".
"To us it is hot" may be a literal rendering but it's not a good English translation -- it does not convey the same meaning to an English speaker as the German sentence does to a German speaker.