I have a question. Do any of the addons for fallout new vegas allow you to keep playing after the end of the main story. Also what is the highest level that can be reached if you get all of the addons for New Vegas. Thanks.

None of the continue after the end.

Your character has too much of an impact on the Mojave for that to be possible without four or so more games made into a DLC.

And the maximum level is 50 with all of them.

None of the DLC's allow you to play past the ending and with all of them the level cap would be 50, unless you take the logans loophole trait, which locks it at 30 but makes you immune to be coming addicted to chems.

Edit:

Ok thanks.