Each registry is free to sell its domain the way it wishes, and some do premiums, some do not.
Although it is a very broad subject, it seems to me it is quite covered in passages containing the word premium here:
How to ensure I always buy an informative domain in the lowest price possible? or
Should renewal price of gTLD will always be identical to the ...
Make sure you 301 redirect your .in pages to the new ones on .com.
.com is considered a general domain which could be associated with any region. You can control this in Google Search Console under the legacy tool of "international targeting" then the Country tab.
Opinion is that there is no real negative global impact on targeting a country.