My question is do these listed prices include one year registration or it is separate?
You should ask the provider, it should be clearly explained.
You could suppose it includes one year extension BUT how transfers work depend on TLDs, hence registries, so you need to have the authoritative answer from your registrar.
At registry level, a
.com like any other gTLD is extended by one year for a transfer (if not over the 10 years maximum limit required by ICANN). But a registrar is free to show its prices anyway it wants and can say: transfer is X on top of Y for the added year (and there is the ICANN fee that can be presented separately or not)
And do I lose any remaining dates registered on the old registrar when I move to a new one?
In gTLDs, a transfer adds one year to the current expiration dates (except corner cases), so the end result is the same no matter when you do it during the lifetime of your domains.
With some constraints:
- you can not transfer during the 60 days after a creation (or potentially a former transfer)
- you shouldn't attempt transfer "around" the expiration date because it may work but you may have difficulties and even double payments (at old and new registrar); based on the rule above with the expiration date being extended, there is no reason to wait for the last moment to transfer it.