Yes. There is a myth that absentee ballots only get counted if the election is close, however, this is not true. Under Iowa law, every ballot must be counted.

Yes. Iowa law allows for Election Day registration if you are able to provide proof of identification (i.e. valid photo ID) and proof of residency (i.e. utility bill with your name on it if your ID has an outdated address on it). If you are unable to provide one or both of these you are allowed to bring someone with you to attest that you have the right to vote.