I recommend you take a look at
HydroGuy's A DLR Guide for WDW Vets. It'll help give you a sense of the differences (there are a lot of them) and similarities between the two resorts. The biggest difference is that DLR doesn't require (or even allow for) as much planning as WDW.
In terms of the number of days, that depends on what you want to do. I would recommend a minimum of three-days, but you'll need to prioritize which attractions, shows, and characters you'd like to meet. If you wanted to do more (or do things at a more leisurely rate), I'd consider five days.
Where to stay depends a lot on your budget and what kind of place you're looking for. There are three onsite hotels and then several motels nearby (within walking distance). I've stayed at the Best Western Park Place Inn, BW Anaheim Inn, Fairfield Inn, and the Courtyard by Marriot (hotel). The Courtyard was the nicest, but it was also the most expensive. The BWPPI is the closest and that's where we usually stay.
Next summer is hard to predict at this point. DLR is slated to open Star Wars Land in the summer, but they haven't said when. Due to the changes in the AP calendar, the guessing is that it's got a target date of sometime in June. If you go after it opens, then the crowds are expected to be huge. If go before it opens, the crowds will probably be okay (still busy, but not insane). So if you're trying to avoid the crowds, I would aim to go as early in the summer as possible (before Memorial Day weekend to be safe).