Yes, you’ve uderstood correctly.
You can use images like a smartphone, laptop and desktop combination only to show that your theme is responsive as that’s an example of illustrating compatibility of your item.
So, if I’ve unserstood, we can use in an image slider a smartphone to show that our theme is responsive (“image used to illustrate compatibility with the real world product”). But, we can’t use an identificable smartphone (iPhone for example). Or only “trademark” smartphones?
1&2 – Sopranos – Breaking Bad
3&4 The Wire – The Shield
So we can’t use an iPhone, MacBook etc, in the slider of the homepage (like the 99% of the themes) now?
Only “Espresso” in Italy.
Well I imagine if you’ve ever told an author their $10,000 theme that they’re selling for $40 isn’t worth that amount after going through a rigorous testing and quality checking process they’d be pretty annoyed.
Support isn’t required and if an author chooses to give away their time for free it’s up to them completely.
If you chance the theme requirements eg if it says it works on WP3.1 and you update to WP3.2 it might push a few things out (Admittedly it shouldn’t) but that’d be on your shoulders as they clearly state it works for 3.1If you feel like the theme has bugs try and be respectful to the author (however had it might be) and send them a message or add a ticket / thread on their support system. If nothing comes from it you can always ask for a refund from support