When should cyclists use pedestrian facilities? I generally try to ride in traffic as a vehicle, following the rules of the road, stopping at red lights, taking the lane, etc. In many urban areas, you are not allowed to ride on the sidewalk (pavement for those from the UK). However, there are some times when it is unavoidable to ride more like a pedestrian than a vehicle, and I have some trouble figuring out when, or how, I should "switch modes."

Some examples:


Most bike racks are on the sidewalk. It feels silly to stop and walk my bike for the handful of yards from the street to the bike rack.
Some bike paths are accessible only from the sidewalk, not directly from the street.
When I stop at a stop light, and it goes to an all-way pedestrian walk signal. While I normally try to follow all the rules that a car will follow, it seems silly to wait (and get in the way of the first car while I'm accelerating) when I can just ride across the intersection on the walk signal.
Some complicated intersections are dangerous to traverse on a bike, but have nearby crosswalks which may be easier to use.
Some bike paths cross streets with a cross walk, which are generally intended for people who are going at pedestrian speed, not bike speed.


Some issues that I have:


Cars likely don't expect to be watching for people riding onto or off of the sidewalk. If, for instance, I need to make a left turn and go up on the sidewalk for a bit to get onto a bike path, I worry that drivers who aren't expecting traffic to go that way might not predict accurately where I'm going.
I feel like using crosswalks and cross lights weakens the "same road, same rules" type campaigns to help give bicyclists access to the roads.
I'm sometimes not sure when it's acceptable to switch modes. There are some cases where I can cut through some pedestrian paths, and ride on the sidewalk for a few hundred feet, or I can go around a couple of blocks on the road; should I be "cheating" a bit by riding on the sidewalk briefly, especially given that there are all of the circumstances listed above in which you need to ride on the sidewalk, or should I be trying to always treat myself as a vehicle and never use the sidewalk unless absolutely necessary?
In most cases it's a matter of common sense and good judgement. 

If the pavement between the road and the bike racks is quiet and you're not going to impede anyone, cycle it. Same for the bike path not directly accessed from the road. 

Your 3rd point, though is the crux of many discussions and we should be careful in how to answer it here. My perspective, although it's not clear whether this is the (UK) legal situation, but just how I 'morally' feel, is that if you approach the junction on a bike you shouldn't confuse the situation by morphing into a pedestrian and pushing your bike through the junction, then remounting your bike. While this might seem expedient it is reinforcing the view of other road users that you're somehow less than a proper road user, if you can use other facilities, then you should all the time, says that argument. 

Certainly there are some intersections where it might be safer to do so, but the law (and cyclists' reputations) are often contrary to safety. It's a tricky question and common sense is often not to the fore in confrontations. 

I try to avoid any use of the pavement unless it is explicitly marked as shared use, but where it's not clear, to try to not do things that would blatantly and needlessly annoy others. After all, cyclists in many locales have a bad reputation for selfish behaviour, I'd rather not add to it.