1.  There are no 1000watt HTIBs as the power ratings are inflated.  The ratings for individual componentry is likely to be more honest.

2.  Power differences between the Sony AVRs is inconsequential.  You need to see a doubling in power to enjoy a real difference.

3.  3D is Bluray, so the listing differences for the AVRs are inconsequential.  You need a 3d BR player to play 3D discs.

4.  I am unfamiliar with those Sonys so I cannot help you distinguish them.  It is likely that there are feature differences.

5.  You might try our sister publication at http://www.hometheater.com/ where they are possibly more familiar with such products.

Kal

First; you need to have a 3d Blu-ray player if you want to watch 3d, period.

Second, there is no such thing as "3d sound". There are various sound encoding formats for home theatre, but they have nothing to do with whether you are watching 3d or not.

Third; since you only have two speakers, I assume that you are not going to do 5-channel sound at this time (or ever?).

Fourth; To watch 3d, you need a receiver that Sony (or some other manufacturer) describes as having "3d pass-through".

The receiver that will do exactly what you want is the Sony STR-DH520, which has plenty of power and is available from Amazon for $177 at this time (Sony sells it for $249). I definitely advise you to buy this one unless you are certain that it lacks some feature you need. (the STR-DH720 has somewhat different features, and sells for about $220, but from what you say it seems doubtful that you want it)

The DH-520 receiver will give you the capability to go to 5-channel surround sound later if you wish to simply by buying a center and rear speakers. Most people who watch a lot of movies choose to do this eventually, but 2 channels works fine for me.

When/if you are ready to do this, Amazon has the Sony CN-5000 center speaker for $70 and the SS-B1000 rear speakers for $43/pair. They should be an appropriate match for the front speakers you have now.

If you ever want to upgrade to better speakers, this receiver has plenty of power to drive 80% of the speakers on the market; that should be a non-issue. Upgrading to some relatively high-quality speakers in the future will be a major expense, however ($600-1000).

The ratings on these receivers are deceptive to the novice. A receiver such as this one that is rated for 100 watts per channel and has seven channels does NOT have a 700-watt capability. It probably has a peak total output capability of maybe 400 watts (which is all you will ever need).  It will be designed to put out 100 watts per channel on the two front channels while supplying lesser amounts to the other channels, but not 100 watts to all seven channels simultaneously. The ratings are extremely deceptive.

Each channel may be capable of 100 watts, but the POWER SUPPLY cannot power all seven channels to full power simultaneously (and it is unlikely that it would ever need to, so to keep the price down they don't provide that kind of capability). Where Sony says that the total power available from the DH520 is 945W; that is absolute bullshit! You can only get that ridiculous number by ignoring reality and adding up things that shouldn't be added up.

P.S.- Any person who is intelligent enough to ask for the information he needs is certainly not an idiot...lol.