Good on you doing all this! The best way to learn is to try. I have had good luck this year with my salad greens, although I didn't plant any spinach at all. I have Bibb lettuce and a mesclun mix (as mentioned by fritz). Some of the mesclun mix has begun to bolt, but some of the plants are still doing OK. I hope to get a couple more cuttings before it becomes too warm for them. I cut from all the plants (selecting a few of the larger leaves) every couple of days and it has seemed to work well.
My radishes are bolting now, too. That last planting germinated, but they aren't doing well, as it has gotten too hot.
Good luck with your summer veges... did you direct plant them? My squash (summer and zucchini) are getting ready to really start producing. I have many small (3" or so) all over both types of squash plants. I'm also getting small cucumbers and butternuts growing well. Pumpkins and Hopi Pale Grey are looking good, too.
We already pulled out the red potatoes and they are very good. We'll have to do more next summer. I've got sweet potato slips that have just recently been planted and are doing well, so I hope we see a decent crop. My broccoli is doing fairly well, but I'm afraid I may have to harvest them before the heads are very big because of the warm weather. The cabbage is looking good, but I'm afraid it could also bolt, as I really didn't plant them soon enough. I do have rutabagas and kale that are still doing ok as it gets warmer, but I'm also focusing more on the warm weather plants -- tomatoes, peppers, green beans, etc. We've had a couple of meals with our own green beans already, but they are still just getting started.
I've ordered a "Marvel of Four Seasons" lettuce that I plan to try out for a fall planting... MIGardener.com has very reasonable seed packets.