1. do a "search" on this site for "blow by" (excessive crank-
case pressure which may be forcing oil from top of engine
through hose to air cleaner chamber)
2. the other two symptoms you mention, in conjunction
with excessive crankcase pressure MAY point to ring/
cylinder wall wear.

How easily/quickly does it start on a cold morning ?
Does it smoke excessivley under acceleration ?

Compression check and a "leak down" test are
definitive tests