Replacing d15 with d13 engine

Hi guys. Its been a long time I asked u any question and I always respect your recommendations.

i have recently replaced my d13 engine with d15 only the assembly i.E. Block, head, ring piston tappet, timing belt which came with the engine, the previous one had a damaged block.

i hv run it for about 30km and checked while running the engine that the water is all clear in the radiator but is giving a delayed bubble?

secondly what are the pros and cons, the engine is Japanese and slightly used?

thirdly the other problem I am getting so far that the rear bottom mounting is causing too much body vibration during starting the car and while running it as well and my technician has advised me to replace it (will make adjustments or install new one) which he shall do it on monday.

the other things which I have replaced are

complete radiator (new)
transmission oil as it is auto (new)
engine oil (new)
front foundation (new)

fourthly also tell me how much fuel efficiency would be effected with this engine?

all parts are honda genuine parts like radiator and lubricants

please reply soon cuz im in a hurry and very much disturbed by these issues

regards,
kashif (Mr.)