Haloalkanes and Haloarenes Part 1

The mechanism of SN1 reaction is given as :
A student writes general characteristics based on the given mechanism as :
(a) The reaction is favoured by weak nucleophiles
(b) R⊕ would be easily formed if the substituents are bulky
(c) The reaction is accompained by recemization
(d) The reaction is favoured by non-polar solvents.
Which observations are correct?