Is the glass crystal on the watch rounded or flat?

Its flat and smudges easily. Simply wash it under a faucet once in awhile. If there are No Dirt Particles or Sand I use a clean microfiber cloth to shine the crystal and watch band. Give it a first time manual wind using the screw in crown. My watch is keeping great time with my cell phone. Its not too fast or too slow.My screw in crown loosened on its own when wearing the watch. I check mine once a week and give it a manual wind. Mine was fine under a bathroom faucet using cold water. Unscrew the locking crown counter clockwise just until you feel the crown pop out a little. Now its in A. winding position. Next wind it clockwise 50 times. It should be good for 41 hrs. ( B. Date and C. Time do not wind the watch ) The customer service said screw the crown in until it stops but not too tight. My local jeweler said too tight can damage the crown. Do not adjust the Date between 9PM and 4AM to avoid malfunction. When setting the Time rotate the hands clockwise. Its better for the movement.

what is that little number on the side of the watch in black and white?

Looks to me that you are inquiring abut the Date window. There are no other black and white numbers on the side of the watch. Sincerely

How to adjust date indication?

Pull the crown half way, that should allow you to adjust the date without changing time. If the minute moves, you passed the mid position.

How long its this watch?

How long? Not sure what you mean. Case is 40 mm. I'm a big guy and I had to take two links out of band to make it fit. Band on this watch was not up to par. Clasp broke after two weeks. Paid a total of $80 to fix it, including shipping. Invicta no help. Repair lasted two weeks and broke again. Repaired two more times and broke after each repair. Finally ordered a new band. Only on my second day with new band. Invicta customer service is very poor. I have two other Invicta watches that have been trouble free. Customer service is very poor. Never got a response to multiple e-mails. Will probably not order from them again. Watch is nice. Zero customer service.