What Seijaku said is right on the money, but with that said, helpful stuff for all comics in general re: your questions -
"What is your biggest/most frequent complaint about webcomics? About plot? Characters? Etcetera?"
If you choose to do something more complex than a comic strip which is meant to be a gag, then your choice of paneling and framing needs to be understood as a way to
carry the story and not a way to simply show that things are happening. What you decide to focus on is a powerhouse of a narrative tool, and it also makes for a comic that is visually engaging to look at. A lot of comics that you can find by people who are eager to get done with a page or maybe not very confident/patient with their art will rely on the same shots all the time, and talking heads.
Zombie Ranch is an example where you can have very interesting ideas and decent paneling and writing and hooks (like the kid that gets bitten early not acting like he should be acting - what's going on in his head?) but the art is so monotonous you feel like reading it is actually a chore. This doesn't mean every panel you draw should look like some lovingly rendered, professional action film with crazy dynamic angles. It just means that a really good way that art can KILL a comic regardless of content, is monotony.
There are some comics that have repetitive angles and shots, but only because this is a deliberate design choice and not because the person who made the comic forgot to consider how incredibly important the camera is.
Do you prefer regular release of small portions (single strips/pages) or less frequent releases of a lot of content (chapters,ect)?
You will probably be able to expect to see readers subscribe to your comic when you have about 15-20 pages done. This is because that way, regardless of your pacing, you should have at least one or two good hooks in there that engage a reader's attention, so they'll want to come back AND because when they see you commit to 20 pages they know you're actually serious and this has a better chance of actually being updated.
Then, the updates - Whatever you say the installments will be, whether it's, "One page every Wednesday" or "Issue 2 coming January 2014", what matters is if you actually DELIVER on (or before) that date. You must be reliable. A reader will take you as seriously as you take yourself. Webcomics that adhere to their update schedules are much more popular than comics that update sporadically because people know to come back and actually expect plot development. And don't update with standalone art when you say "one page every Wednesday," either. Random comic-related art/splash art is cool, but it effects the pacing of a narrative and shouldn't be put in just 'cause you felt like showing the world this here picture of ____. A poorly planned splash picture that exists just to be pretty is usually a disappointment to a reader because they expected a comic page, not an artsy graphic. That's what your gallery is for.