Wow, big question. Here we go...

First, I recommend following the link Emory posted and read up. If you still need advice:

1. how do you translate effectively "down" your perspectives of life/next 5-10 years/next 1-2 years/next month/next week/now? How do you make sure that you're doing things, in your day to day, in a way that reflects your bigger goals in life?

I think you should have a review system which enables you to trust that you're doing what you're "supposed to be doing", according to your bigger picture priorities, but I coulnd't see any specific advice about how to install a technique in your reviews, to actually do that.

What you are dealing with was one of the more difficult concepts of GTD for me to understand. I was used to a life management system of "setting priorities", so when starting GTD my concern was that I would simply be doing battle with daily minutia and would forget about the larger picture. However, the opposite occured. GTD allowed me to get control of the daily grind and gain a higher focus.

Perspectives of life (I call them "areas of life") produce (or at least should produce) the bulk of our goals, projects and NAs. I set goals to improve these areas and then let the projects & NAs flow from the goals. However, areas of life should also produce projects & NAs that will help us maintain our performance in these areas.

Some examples might help. For instance, one of my life areas is "husband". One of the goals tied to this area of my life is to earn more money (the actual goal is "earn $xx,xxx by xx/xx/xx"). To some that may be a "professional" goal, but to me it really relates to one of my responsibilities as a husband. The project that has come from this goal is "Earn ____ certification". That project has then been broken down into NAs and placed into my trusted system.

In addition to setting goals for this area, I also want to stay in touch with my ongoing responsibilities in the area of being a husband. What has helped me in this area is using checklists during my weekly review. That way, every week (or 2 :o ) I'm looking at a list of what I should be doing to keep up with my responsibilities in that area. This then generates projects (take wife to dinner at Vincenzo's) and NAs (call wife and ask how her day is going - @Office).

I do this by using an Excel file with tabs labeled "Areas of life", "Goals", "Checklists", etc; that I refer to during my WR. It works very well but only as long as you are doing consistent WRs.

2. assuming that your next actions list is going be be quite big, or in other words - you generate next actions faster than you can do them - how do you avoid the feeling of always being behind on things? how do you get a sense of "ok, I've done the 'important' things this week, I can call it a successful week" if you', by definition, never completely finish EVERYTHING you feel you need to do?

This used to be a big problem for me. The solution I have come up with is to set up a tab in the same Excel file I mentioned earlier called "W/O Bandwith" (I got the terminology from one of Merlin's posts). It simply means "waiting on bandwith" and represents a list of items that I am committed to, but just don't have the space during the next week to deal with. It is like my "someday/maybe" list with one exception: I have commited to see the items on this list happen, but have decided that during the next week to focus on only the items populating the projects and NA sections of my hipster PDA. Every week at the WR I move projects/NAs from the "W/O bandwith" list to the hipster as space and/or priority dictate.

That's why the WR is so critical. It gives you the chance to decide what is truly most important during the next week, so that at the end you can call it "successful."

Hope some of this can work for you.