Ye, that's one of the problem. I'll try to explain all of them...
1. As you are using Recent Projects to open your project, it uses the previous path for the project. And when you change the project folder's path, it's creating problem.
2. Yes .prj / .project files are VB specific, if you want to see those files you need to enable "Show Extension for Recognized Files" on Folder Options depending on the OS you use.
3. I guess you are using Win Vista / Win 7 / Win 8. In any of the cases, you need to open VB6 as "Run as Administrator", as your project file is under Program Files, OS above Win XP doesn't get native rights to write to that folder. And that's why you are facing the problem of saving each of the form in that way (as you said above). Open VB6 as Run as Administrator and your this problem will be solved.
Else copy the project folder to somewhere else (Other than C), and try to open the project in VB from File > Open. Again start VB as Run as Administrator.
Hope that helps. Let me know
Ok, this is specific to programming, I'll try to jot down the steps here...
1. Declare a public variable in Form2.
2. Now whenever someone selects something in Data Grid, set the public variable of Form2 to the ID of the selected Row and open Form2.
That's it
NOTE : I used VB6 around 3 years ago, so I'm not sure which event occurs while selecting rows in Datagrid in VB
So please google the appropriate Event do the steps mentioned above in that event