Sound edit for a short film

Some friends and I made a short film - as a crew of amateurs! - for the fun of it but we've decided we like it and would like to submit it to film festivals. Knowing the importance of audio for professionalism, we don't want to do it ourselves but would rather hire someone who actually knows what they're doing.

Personally, I know virtually nothing about audio, but I've spoken to some people and think the following is important for you to know:
The film has a run time of about 6min
The are some specific sound design elements I want included, but nothing fancy.
I might need a bit of supporting foley (e.g. there's a train but I have no audio to match)
Stereo (which I think is what we recorded in)
A lot of it is set (and shot) on a beach, but the audio is quite clear for the most part. We don't have an option of any ADR anyway.

I'm recording the score soon and don't have a mixer for that either, if that's also something you could do.

I'm paying for this myself with my savings, but I am willing to pay a good rate for the right person. We really don't want to be turned away from a good festival just because the sound is bad - it has become quite a passion project! Budget is a placeholder, I have no idea what the normal rate is for this!

I look forward to all your responses!