SH4 noob, overwhelmed with mod options

[Panser]

I've decided I would like a change of pace from SH3, a game I have been playing on and off for 5 years. For the first time I have picked up SH4 with the U-Boat missions add-on. I'd previously overlooked SH4 since release given that I had little or no interest in US sub operations, a position no doubt not helped by my general ignorance of the topic and the lack of attention the subject generally receives in the UK.

Still, being something I would not normally go for I figure it would make an ideal change. I installed the game the other day and have finished the training school missions a couple of times and went a lot better than expected.

Having read around on here I get the impression that using some of the available mods is highly recommended, even for new players, and this is where I have come unstuck. Options to enhance the US side, options to enhance the UBM addon, even atlantic operations. I've been truly missing out all this time and now don't even know where to start. The mechanics of using mods with JSGME is not the problem, just the choice of what to use and with what else.

I guess my post falls into three questions, one more open than the other two.

1) Are there any mods for SH4 that are analogous to the GWX/NYGM supermods for SH3 in terms of scale and completeness?

2) Can mods for different theatres and nationalities be installed side by side, or do I have to make a choice / run multiple installs? Specifically, can I run any of the US PTO mods and UBM mods in parallel or are they mutually exclusive?

3) Lastly, what are considered to be popular and/or reliable combinations of mods for the various facets of gameplay (US/German/ATO)? Obviously something as subjective as "the best" is pointless to ask but hopefully there will be a general consensus on which mods are complementary to one another.

Sorry to post such a wall of text and I thank anyone who has reached this far for their patience. Again, I appreciate that most of this information is out there already but I have looked through the forums, searched and looked at my options on the downloads section and have not really found found the answers I'm looking for in a manner that I understand.