Exactly what it says in the tin.
A language based on Vulgar Latin, but with a Slavic substrate.
PoD is around 100 AD, and Romanian doesn't count for the purposes of the OP.
Romanian is pretty much this. A romance language with a lot of slavic hybrids.
Not really. ....In a lot of ways, Romanian is like English. Both languages saw a huge amount of borrowing from the languages of the people who ruled them for centuries.
Not really. The slavic elements in Romanian are mainly vocab (apart from the numeral system, which is unique). The grammar and syntax are inherently Romance. In a lot of ways, Romanian is like English. Both languages saw a huge amount of borrowing from the languages of the people who ruled them for centuries, but the borrowings tend to be specifically focussed. Urban life, military, government, wealth and prestige, these tend to be the areas that see the most borrowing, whereas the home, the family, the land, the farm, the church, these areas tended to see the least amount of borrowing.
And is it different from the relation of the other Romance Languages and their Germanic Substrate? This is pretty much the definition of Linguistic Substrate. Most part of the "artificial" borrowings in Romanian are the French ones from the 19th century. Before that, they even used the "slavic alphabet" - Cyrillic alphabet.