Instead of having separate installers for 32bit/64bit why don't you just have one universal installer
It would make it easier for new users who have no idea about this. Along with this I would really like
an automatic updater that grabs the latest version without having to visit the website, Even just an
option of this would be a real convenience for me :) I hope you consider it.

Apart from that I think the product is awesome

Universal installer that contains both 32/64 bit version will be twice as large, which seems like a huge waste of bandwidth, both for the users that are downloading it and Tixati web site who would see 2x bandwidth on their servers.

That's a huge waste of resources for a very small amount of hapless clueless people (seriously who doesn't know if they are on 64 bit computer, maybe grandparents? but they don't torrent generally) and besides, the first one listed is the 32 bit which will work everywhere just fine.

Automatic updates are a VERY BAD idea security-wise for both users and devs alike.  It's not great to give ANYONE an AUTOMATED remote pathway to send arbitrary executable code to your computer, no matter how much precautions and encryption and security checks.  It provides too tempting a target for a 3rd party attacker.  Keys can be leaked, servers can be hijacked.  Not worth such risks considering updates are usually months apart aside from the occasional spurt of 2 or 3 within a few weeks.  Look at the news page for the historical timeline.