Forecast is entered in MR-A and there is a setting in MR-M (Evo-ERP Admin menu) to include the forecast in stock status.
 
RM is RMA and SR is Service/Repair orders

Have you actually entered Forecast quantities in MR-A?

Same situation here.

So, how is this supposed to work? The forecast is forecasted sales, yes? Do you want those subtracted from the Available to show shortages in availability? Or are they forecasted builds that you want added to availability? The help file seems to be telling me that forecasts would show up like sales orders, which should subtract from available stock and affect MRP accordingly.

You forecast sales for items other than finished goods? Sounds a bit odd, but...

Usage of parts trickles down from forecasted sales through BOMs. You forecast selling 100 doodads and MRP tells you how many parts you need (and when) so you can make those doodads. You can also set a reorder point (safety stock) for individual parts so that you will have a few extra in case of scrap, repairs, late vendors, etc. The bear is entering lead time and other MRP info for the hundreds of parts that going into the dozens of items that you forecast... or the thousands of parts that go into the hundred items in your forecast  

My understanding of the system would suggest that OEM stuff (purchased ready for sale) should be class F. We have a few items of that sort.  
 
And yes, the help on forecasting states plainly that it operates on type F only.

Probably not, as long as you have put them in various classes. We lump almost all Type R and Type A parts into a raw materials class. We have various classes for Type N (expenses) and Type F (income) items to track expense and income by category. If you are taking the time to put each Type R item into a class that has both expense and income GLs set to toss the debits and credits into the right buckets it does not matter which of the two types you set.

The Forecast field on IN-A was added at the request of a customer who we were doing some other customization for.  For the next update, we will make it include all part types because as you point out, you may have R parts that are bought and resold.  To clarify how this will work, IN-A will first look to see if the part being loaded on the screen has any forecast (as entered in MR-A) and if so, add up if there are multiple records for a total forecasted quantity.  It will also look one level up into BOM parents it goes into and if any of those have a forecast, it will also include them.  We will not traverse the BOM more than one level because we feel it would slow IN-A down too much.  If you have deeper BOMs and a need to see the impact of forecast on demand you will have to look at the reports in MRP.

Yes, that seems like a good balance.