How easy is it to get research opportunities as a freshman, sophomore? – I didn’t try until junior year, but I know people who started sophomore year or who did something on campus during the summer after freshman year. Check out this page for ideas if you haven’t already: http://www.eecs.psu.edu/students/undergraduate/Research-Opportunities.aspx
Are your professors approachable and available? – If you make an effort, go to office hours, and let them get to know you, yes.
Are the research opportunities easy to get and if so do most students participate in research? – I would say most students do not participate in research. The people who tend to participate are either aiming for grad school, Schreyer scholars (we’re required to), or just very very interested in their field. I only had to ask one professor and he said yes (fall of junior year), so I don’t think the positions are super competitive but you may or may not get the first position you ask about. Chances are better if you get to know the professor first.
How involved can a student get in research? – I am not quite sure what this means so I’ll just give my own experience. I joined a lab (computational research, not like going in to do experiments) fall semester of junior year. Now, in the spring, I am helping the professor write an article to submit to a journal (on which I believe I’ll be fifth author because this topic has never been published before and there were several students before me who helped develop the theory). This article will then be the core of my thesis next semester. So I’m not doing trivial stuff or anything. You won’t just be washing beakers or writing down numbers someone else dictates to you. At least not after you learn the ropes in that lab.
Are students permitted to use the labs/ machine shops outside of research? – Not sure since ChemE’s don’t really machine anything. Computer labs (in each commons area, in the library, in honors housing, and in some departments) are generally open. That might be a question to ask of your department by phone / email. The general counselor at NSO won’t know.
Have you had any problems getting into classes? – No, but I schedule early so I’m not the most representative sample. Many of the lower-level classes will be offered in multiple sections, so you may not always get your preferred time, but you will likely get a seat. Labs can fill up fast, however.
Do you recommend using AP credits (Calc AB/BC, Chem, Physics Mech, Physics E&M)? – Try a practice final for the classes (usually available online if you google “penn state math 140 final” etc – will bring up the teacher’s website, or a department-run test bank, or something). If you can do it pretty well, consider skipping the class. If it’s been a while since you earned those AP credits (ex. I took AP Chem junior year), consider retaking (I didn’t want to jump into organic chemistry without a refresher) unless your recommended academic plan says, for instance, that’s the only chem you’ll ever take, in which case you probably don’t really need it and can skip it. You might want to skip the chem labs either way. That’s four hours of your week you’d never get back.