would this work using half and half rather than heavy cream?

If your ‘cream’ alternative doesn’t have enough fat, the lemon juice will cause it to curdle.

The only challenge I see is that you are supposed to bring the cream to a boil so it thickens slightly before pouring over the pasta. If you boil half and half as it is, it may well separate and curdle. You can try to overcome this tendency by adding in a tablespoon of butter for each cup of half and half, as well as not actually bringing it to a boil. Or you could opt to put the half and half in a pan large enough to contain both it and the pasta, remove the pasta from the water a few minutes ahead of being done, add it to the sauce and finish cooking in the sauce. Residual starches from the pasta might provide enough to stabilize and thicken your final product as it cools. But if you don't mind a thinner sauce, you could just heat the half and half short of boiling and pour it over the finished pasta. After all, that's what bread is good for.

Yes.
If that's what you have and want to use.
If you want a richer taste than half and half, finish with a spoon or two of butter, cream cheese or mascarpone.