-ishte, -eshte

Are these "-ishte", "-eshte" slavic suffixes
-ishte is found in slavic languages( as I read) and in
romanian too.

In romanian "-ishte" is used just for making substantivs like
porumb+ishte= porumbishte

"-eshte" is for making an adverb
prost :prostesc prosteshte
but is to find in conjugation of the verbs at the III person
singular
vorbeshte, spoieshte, abureshte, dadaceshte, gandeshte,
tavaleshte, etc..



I found contradictory explanations and contradictory opinions
about them So are they to see as beeing a only suffix ore are
there indeed two?
Is a simple vowel ( in this case e and i) a signf for a surely
appartenence of a suffix to language / language group?