When it comes to cutting, you should be doing at least 30 minutes of LI 4-5 times a week (or something comparable like 10-15 minutes of HIIT). HIIT is much more muscle sparing than LI so if you have the energy for it after a workout, then I'd suggest you do .
There have been some articles proving that during cardio, your anabolic response will be suppressed. What this means is that doing it after weights will prolong your catabolic state. In an ideal situation, cardio should be separate from weights. In real life, and considering you're a hefty guy, cardio anytime you can fit it in is better than no cardio at all.
When it comes to workout nutrition, if you pair cardio and weights together, I'd sip on something during cardio.
As far as HIIT options go, I'd consider anything on an elliptical not be real HIIT. It's too easy and not really HIIT. My first go to is always sprinting. Second would be sprints on a bike at a hard gear, 3rd is incline walking intervals on a treadmill. That's just my personal preference, but you do what you like. But if it's HIIT, usually whatever hurts the most works the best, and that won't be the option you like