I've been using the swing top bottles for most of my brews (the other's go into Belgian bottles)... Since I don't have a dishwasher (other than my own two hands) I simply wash them out as I empty the bottle (it's not difficult to get them clean) and store them until bottling day. I have a bucket of StarSan mixed up and simply fill the bottles in the bucket (submerge them, letting them fill up) and then drain them out. I have a sanitized bottle tree right next to me for the bottles to go onto...
During the bottling process, I'll use either a towel saturated with StarSan, or my spray bottle filled with StarSan, to sanitize the gaskets before capping each filled bottle.
I really do like using these bottles, since it means I don't have caps to worry about having, crimping on, and more stuff to toss out per batch. If you compare the cost of the consumable items with the swing top bottles with capped bottles, the gaskets pay for themselves within two fillings. Since you get at least 5-6 fillings out of each gasket, you end up saving money there. I've not compared prices against the 12oz bottles (just the bottles) but I like having ~36 bottles for a 5 gallon batch, compared with the ~48 with 12oz bottles. Plus, all my beer glasses are designed to hold a pint, not 12oz...
For pulling a sample of the brew for testing, you can also use a stainless steel baster... You can try the normal sized one, found in many stores, or you can get one of the long ones found at many HBS... I would go with stainless steel over plastic here mostly because you won't need to worry about scratching it and then having infection risks. Personally, I'm using a glass wine thief to pull my samples. I sanitize the thief, and the hydrometer test tube before pulling the sample. It's nice having a bucket of StarSan mixed at all times.
Plus, the spray bottle filled with it comes in handy a lot.