Windows 7 is terrible choice on a touch screen device (almost similar to Windows 8.1 on a PC device). I would recommend 8.1 as a "sweet spot" especially for smaller tablets otherwise there is nothing wrong with Windows 10, if preinstalled on the device. ThinkPad brand tablets are dead, there is ThinkPad 10 tablet 2nd Gen edition but it is just terribly overpriced average tablet, nothing more.
All Lenovo (and other vendors) consumer tablets (Miix and Yoga) have issues because there is no longer any quality control and no testing (and no support). Typical issues are that wireless devices stops working after wakeup from sleep mode and so on. The reason is pending bugs in BIOS and drivers because nobody has ever tested these devices before the release. Sometimes an update (if Lenovo bothers) helps but it is better to check issues in Lenovo forums
for particular selected model before the purchase (there is famous Yoga 2 10 tablet wake up issue
Lenovo has never resolved).
Depending on your display size preference, Miix tablets (or rather 2-in-1 with detachable keyboard) seems to be a good option.
I am not sure whether the USB port on tablet can deliver power for an external CD ROM. It is a bit awkward setup these days