If I was to train twice a day here and there during the week, is there anything specific (land based) that you recommend I do?
I would recommend rotating through a ruck, cals, stretching, and grass and guerrillas with stretching and foam rolling being the most important. I don't want you to get injured so just make sure you are really listening to your body.
I have heard the new A&S is mainly land based now, is this true?
The new A&S is more land than water now however, you will still have all of the watercon aspects when you get to predive. So I would absolutely not stop practicing your water work.