In terms of October weeks, there is nothing "major" that has been announced in terms of events, conventions, etc. (at this point). That being said, as
fantasmicfantastic mentioned, HalloweenTime will be going on in DLR, which does tend to mean higher crowds than other times of the year (outside of peak-season). HalloweenTime is very popular in DLR, but at this point, we don't know a lot about how it will look in 2015. MHP have, historically, been held in
Disneyland. We don't yet know the dates for the parties and probably won't know until either very late this month or sometime in July (assuming they release information on the same timeline as in past years). Keep an eye on the Disney Parks Blog and here on the Disboards for information about HalloweenTime and MHP (once the dates are posted, I'll add them to the
2015 Calendar Thread and there is also the
HalloweenTime SuperThread).
You're going going from a Monday to a Thursday, which should help with crowds, but it's worth noting that in the non-peak season, they usually do not present fireworks, F!, or Mad T Party on Mon through Thursday. WoC is typically presented nightly and we do not yet know know what PtN's schedule will be like in the Fall (nightly or only on weekends).
There are a few school districts in CA and surrounding states that are off that week for Fall break, but I don't think it's going to have a huge impact on crowds. UEA is the week before, so luckily you won't be contending with that (though there might some residual crowds on Monday for a few schools that are still off in Utah that day).
In general the parks will be operating on a shorter operating day (e.g., DL's hours may be something like 10:00 am to 8:00 pm on weekdays or 8:00 am to 6:00 pm on days when there is a MHP). You can look at
last year's calendar to get a sense of what the hours may be like.
As mentioned, HMH and SM:GG will be up and running (baring some major change in HalloweenTime, which seems unlikely). There are other HalloweenTime activities (such as the Big Thunder Halloween Carnival) and decorations in the parks. SMGG has FPs (Space has a year around FP system), but HMH uses the FP -system intermittently, depending on crowds. It will be interesting to see how much of HalloweenTime is impacted by the 60th Anniversary. There is a lot of speculation at this point, but no one really knows what will happen yet.
In terms of wait times, I don't think you're going to see 30 to 45 minute waits for most rides, but I wouldn't be surprised if waits for things like SMGG, HMH, RSR, TSMM, etc. were long. I'd guess HMH would be in the 30-45 minute range, TSMM and SMGG are in the 60-90 minute range, and RSR is probably in the 90+ minute range! I don't think rides will be "walk-on" (except perhaps right at opening), but I would guess waits would be more in the 15-30 minute range (except for the headliners).
