Yeah, forests are tough. Altiverb has some good forest verbs.
Try an in game worldized reverb with heavy damping, a short tail and a longer predelay. I've found predelay to be the most important setting for real world verbs like this. It should almost sound like a long slapback verb. Try more than 80ms and experiment.
To answer your first quesiton, very dense and thick foam (properly attached too to prevent vibration transference - as in, not just "set and forget" flopped ont top of the car) should do the trick. That's effectively what the Rycote rain covers are in a general sense - thick and dense over-sized foam to help absorb the rain drop sounds from transferring to ...
Get your dlog levels right, and everything else gets mixed according to that. There's no specific level for ambience (or foley for that matter), it is simply mixed to sit naturally in relation to the dlog. It always frustrated me when people gave me that answer, but it's pretty much the only right answer for that question.
If you're struggling with noisy ...
OK, so if this is one of those utterly random class assignments where you absolutely 'must' do it with 'just an iPhone', the only way to really do this is to record your dialogue 'wild'. This requires the actors to be able to re-deliver the dialogue in-synch and in-performance, but not to camera. You simply run the iPhone over to the actors after a take or a ...
There are only really two ways of reducing the amount of background spill into your dialog track.
Expensive directional mic on a boom
Even more expensive noise-reduction software, eg Izotope RX 7.
In the absence of either, then your next best option is 'any mic' as close to the speaker as possible, whilst keeping it out of shot. Tie mics (lavalier) could ...
I would record room tone at the same level as I have recorded the dialog or whatever I was recording in that room. Then the room will sound the same as in the background of the thing I wanted to record.
I remember, years ago, finding a little freeware program that generates 8 bit synth FX, but i can't remember what it was called. Here is a tool i found that does something similar.
There seem to be quite a few options if you google something like "free 8 bit fx generator". Hope that helps!
If you are in a pinch you could try www.freesound.org.You can find some public domain files there that might help.
Shaun's cloth library is good. @Stavrosound has a link in his comment.
If you are still struggling, take some pink noise, eq it to make it more usable and ride short low bursts of it on larger moves. It's not ideal but I've used it in the ...
First of, sitting well in the mix can be a problem for any element in a design. Making it fit is much more a technical endeavor than a 'realistic/document' design process of the element.
So the distant gunshots treatment can also be 'unrealistic' but still work well. Making it fit is something that comes after the design in my opinion.
Regarding reverbs ...