Not sure about that particular screen settings, but the fbtft driver has been upstreamed into the official kernel sources... TFT screens are now supported by the rpi-update kernel. If you can figure out the correct parameters for the LCD, then you can set up the /etc/modules file to load the fbtft module without having to rely on dodgy images from LCD resellers. The /etc/modules entries will look something like -
fbtft_device name=<devicename> rotate=0
(replacing with the correct device for your screen.)
After that you should be able to upgrade to the rpi-update kernel without losing TFT.
sudo apt-get install rpi-update
The touchscreen is a little harder to get running. If it's resistive, it's probably an ads7846. In that case you'll need to figure out the correct dtoverlay. that'll go in /boot/config.txt once it's sussed. It looks something like -
dtoverlay=ads7846, penirq=22, speed=500000, swapxy=0, pmax=255, xohms=70, xmin=415, xmax=3700, ymin=250, ymax=3850
Oh and as to your other question - In my experience, there are absolutely no 'pro's to using an older kernel supplied by a hardware vendor.
You can also build your own kernel. If you do that you would copy the config of your running kernel from /proc/config.gz then reconfigure and build-> (assumes you have the kernel sources and build env. set up)
cat /proc/config.gz | gunzip > /usr/src/linux/.config