I'm all for
house rules, but I don't think your specific problems really require house rules.
I happen to agree, none of these have ever struck me as problems with the system.
Grind: A simple and effective solution to this problem is to play monsters realistically: when a foe hits the bloodied mark, they flee. And it makes sense too; unless a foe is cornered or is mindless they're going to run once they realize the fight is going bad for them.
I don't agree here. While it's true that players have reserves of healing that monsters often don't, a player group will rarely retreat from a fight even after significant depletion of party resources (like hit points/healing surges/powers). Why wouldn't monster groups do the same, especially if it looks like they still have a fighting chance? Yes, the PCs are insanely suicidal by nature (since you take ridiculous risks as a fictional adventurer that no sane person would ever engage in voluntarily), but if the monsters don't possess the same level of dedication to a fight the PCs will rarely feel challenged. Rather than taking every opportunity to have the monsters flee when plausible, I suggest the opposite: if it's plausible for any reason to have them stick around to finish the fight, have them stick around.
If combat is a grind, look for ways to speed it up. How long is each person's turn? If players are taking more than a minute on average (and more than two minutes at a maximum), they need to speed up their turns - become more familiar with their abilities, plan their actions before they reach their turn, use power cards, etc.
Wizards suck: Play an orb wizard and crank Wis. Very effective, especially at high levels. A common house rule I've seen is to turn wizards spontaneous: instead of prepping their daily and utility slots they cast whichever spells they want. I personally hate that the wizard's spell book became a vestigal bit of fluff in 4e, so I wrote the Power Prep house rule which you might be interested in (follow the link above).
Or just play a Wizard and stop being bad at it. I've seen a number of Wizard characters in games that I've played in or run, and every one of them has been effective and every player has enjoyed playing them. And, for the record, neither of them were orbizards so you don't even need to do that. Re-examine your tactics, cooperate with your party more to make your abilities effective and pop out a daily power every so often to just completely destroy an encounter.
