Hi Anogar,
I live and cycle on the Eastside of Seattle and I can tell you there are plenty of workable bike routes around Bellevue. My personal commuting is not done in or through Bellevue, but I can tell you it's quite doable and you'll see others out commuting.
Some suggestions:
1. Get the bike map from the city of Bellevue. Bellevue streets are laid out on a grid so it can be hard to tell just looking at a regular map which ones are bike friendly. A lot are pretty busy. The city of Bellevue map is a realliy good quick start to the best ways through and across Bellevue by map.
2. If you don't get good answers to your questions here, check out the Pacific Northwest community forum here at bikeforums -- or you can go to the website of the Cascade Bicycle Club. There is a specific message board under their "community" session dedicated to commuters and commuting.
3. You had another post here asking about Gregg's Cycles. They'd be a great first start for any of your equipment questions, especially if you own a Trek. They're probably the biggest Trek dealer in the Seattle. You mentioned, though, that you're living close to Lake Sammamish -- you might actually be closer to downtown Redmond, where there are a couple of good bike shops -- especially Sammamish Valley Cycles.
If you are also going to be riding for recreation, you'll be living in a good spot to get out for longer rides...you can do the lap around Lake Sammamish, head up the bike trail to the Red Hook brewery, bike over the Lake Washington and do the loop around it....etc. etc.
Hope this helps.