Would you read a script I've written and give me comments and/or advice?

I'd rather not.  I'll give you all the advice you want — assuming I can spare the time and you remember that Free Advice is worth exactly what you pay for it.  But I'd rather not read your script.  There are a couple of reasons for this.

One is that I don't particularly enjoy it.  It means yanking my thoughts away from whatever scripts I'm currently writing, and whatever problems they have, and instead devoting some of my brain cells to your script and its problems.  Another is that if I someday write something that's even vaguely similar to your script, I don't want you thinking I ripped you off, consciously or otherwise.  Yet another is that I sometimes find it very unpleasant to tell someone I don't like what they've written.  (A great tip-off that it's going to be an ugly experience is when the wanna-be writer says to you, "Be brutally honest.  If it stinks, don't hesitate to tell me."  Those folks usually get enormously pissy if you offer any criticism more severe than pointing out a typo on page 17.)

But the main thing is that, since I'm not going to buy your script, my opinion of it isn't that important.  No one's is, except for yours and that of any folks like agents, editors or producers whose favorable opinion will cause it to move a little closer to being published or produced or whatever your ultimate goal is.  I've walked out of plenty of movies — some very successful ones that garnered lots of cash and acclaim for their writers — thinking, "Boy, what a lousy script."  If you had written that script on spec, what purpose would it serve for me to tell you what I thought?  One person's opinion is just one person's opinion.  Or, to put it another way: Who cares what I think?

If you do, I think you're making a mistake.  Send your writing to someone who can do something with it.  And if you don't think it's ready for that, write something else or rewrite this one.  The main thing you're going to need to be able to do as a professional writer is to know how to fix your own work.  This might be a good time to start.

For whatever it may be worth: When I was starting out as a professional writer, I occasionally had my work critiqued by folks who were already established.  Their advice was uniformly useless, at least about its contents.  A few did make some good suggestions with regard to formatting and presentation.  That's the kind of wisdom one can get from a veteran writer.  Stick with those kind of questions.