Here is the link to the decision tree http://www.fra.dot.gov/Page/P0417

The entire CFR is available on line both from the GPO and Cornell Law School.

As far as your crossings and the insularity go - If I understand the situation correctly the inventory shows the crossings on the track you acquired as closed. I suspect they are closed because rail operations were discontinued, not because the roads were closed. That being the case further discussion of insularity is unnecessary. You aren't.

You are going to have contact the FRA to obtain an ID code for your operation and then fill out the 6180-71s to have the crossings show as yours and as having been opened. The FRA has a spreadsheet template you can use It may be also worthwhile for you to obtain the GXI software and use that for your record keeping.

Any specific questions feel free to back channel me.

Mike Allen