U-boat types and mods
 

I know that there are VII subs only as a playable units , but there are other types as a IA units ?

If exist as a IA unit could be possible mod it to aditional units, if not the thing could be more difficult or impossible.

Your idea and wish is understandable but I have one question for you, somehow not very on to this particular topic, but to modding in general: Wouldn't have been normal that the devs should have made the game so playable that the request for all kinds of mods should be much lower than actually is in this moment? How can you people accept that so easily? What's wrong with you? The modders should (if they want that, of course) to fine tune the game, not to make a BMW from a Moskvich. That was the devs responsibility (in exchange to their "successful" efforts you were supposed to give UBI money for the game) but it seems they've failed into that in style.
And I suppose you are willing to pay for the upcoming expansions as well: 1943-1945 campaign, other playable subs, and so on ... And for the right of DRM to have fully access to your intimacy of your beloved Personal Computer. But some of you have already done that, I forgot, sorry ...

Well, a long range subs could be useful for caribbean and drumbeat patrols at 1941 or 19, so if ubi don´t release an aditional pack , aditional units can be made using the 3d model of IA boats.

a similar thing like some people made with surface units,and convert it to playables.

Yes, but it also involves designing a campaign for those things :)

Subs will be in, there's no doubt - by mod or official expansion. I agree this should not be top priority right now though. As it stands, I'm actually quite happy with a VII study sim - but wait, we need to put a bit more "study" into it before it can really take up that title. So I definitely say we polish up our VIIs first before turning them into BMWs... or IA for that matter :88)