Do international, college and HS scouting just affect what players you can see, or do they ALSO determine how accurate the projections are? Or is that determined by advanced scouting? 

There was a thread about how advanced scouting was useless, but wouldn't it be useful if you wanted to determine how good a possible interenational prospect or draft pick could be?

The advanced scouting does not kick in until the prospect has been signed. I am a good example. 6 million international scouting and 14 million advanced. I sign a guy who looks good and then his ratings look horrible after he is signed. lol

So a high international scouting is also helpful in determining potential?

Yes it is before you sign the guy. Here is what I am saying. The guy may be rated 55 and have 75 potential before you sign him. After you sign him he may be rated 45 and have 65 potential. After you sign him you are going off of advanced scouting. Before you sign him you are working with your international, college, or high school budget.

That is incorrect.  Everyone sees the same current rating. Scouting budgets affect what one sees for the potential rating, never the current rating. The higher your scouting, the more accurate the potential rating that you see. Int'l, HS, and College also affect how many prospects that you see. Some vets use low Adv scouting precisely because they know the current rating is accurate and they feel that they can extrapolate potential from that with a reasonable degree of accuracy.