1. No, but it's limited to what a holographic object can do, which is largely to mislead rather than grant combat bonuses, which by design other spells do. As a DM, I'm probably not going to be inclined to let a Cantrip match or supersede the power of a 1st level spell.
2. Agree with previous post (no creatures and interaction reveals the sham). It only creates static images that generally mislead. However, in a case-by-case basis, as a DM I might let it have a mechanical effect. Because application would not be consistent (some foes might puzzle it out and be unaffected), from time to time it'd be fine.
So the dirt wall could cause the goblin to believe he has blocked vision (unless he interacts with it or has cause to make a check to disbelieve). That's what the spell does, tricks.
As to the light question, this has been debated before, and an illusion can't actually block anything, whether it be light or sound. It's not real, and it has no substance. So, you can have a lantern hidden in an illusory chest. Anyone walking in would find a lit room with no obvious light source, leading a foe to scratch its head as to what's going on and possibly triggering an Investigation check. Same with creating a mirror. Mirrors work by reflecting light, and a Minor Illusion isn't real so it reflects nothing. A creature would see no reflection in the mirror at all other than perhaps whatever static image the Caster made up.
As for the hole (or a small well), same as the dirt wall.
As for the table, I can see the argument being made that the goblin believes its shot is harder because it's trying to shoot over cover. However, the table has no substance so it doesn't really grant an AC bonus. Further, mechanically, is a DM going to allow a Cantrip to provide a +2 AC effect? Personally, I'd take it case-by-case. The first attack by a monster could be made as if it believed cover existed. Whether it hits or misses, unless it's a "1" fumble, I'm probably ruling the arrow went through the table, the creature has thus physically interacted with the illusion, and the table is revealed (as a low-level Cantrip should be) as a sham. Clever monsters would share this knowledge that there's an illusionist around.
In any case, I wouldn't ever allow it to be equal to or superior to Shield of Faith, Fog Cloud, etc., in providing benefits.
This all goes along with the question "can I create an illusion to Hide behind, therefore granting advantage on my attack?" Like above, yes. If the enemy believes you've gone out of sight (if you're small enough to Hide behind a 5x5 object), they've been misled.
3. Yes, in many forums usually with a specific single issue (e.g. can Minor Illusion grant cover, block light, etc.)