Most of the items you mentioned do not appear to be valid grounds for constructive eviction, but it depends on the facts. For example, was having no power in July something within the landlord's control, or just the fact that PG&E had a power shortage/outage?
A landlord is not responsible for providing a cable outlet (only telephone).
On the other hand, not having any heat would be a ground for constructive eviction. However, it still depends upon the extent of the problem making the apartment uninhabitable.
For more detail on these issues and an explanation of your rights and remedies as a tenant, take a look at:
The safest way to break your lease in this instance is to make sure you document the breach of warranty of habitability issue well.
In real estate, we say "location, location, location", in litigation, "documentation, documentation, documentation.".
The best documentation in this case is the one that comes from a governmental agency. You have to right to contact your local code enforcement officer to come out, inspect, and issue citations against your landlord, if in fact there are health and safety violations.
After he's been cited and if he fails to correct the items on the ticket within 35 days, I think you would then have the documentation that you feel good about to base your constructive eviction on.