So it all pretty much comes down to this - how is the focus? Did you nail 'em?
Your culling process will be vital. Don't be lax with it, because if you are it will bite you on the ass later. Be ruthless.
If there are any that you're uncertain about, feel free to post in this area for my help.
No. The PPI number is completely meaningless, I assure you.
https://www.damiensymonds.net/art_resolution.html
https://www.damiensymonds.net/2011/11/why-ppi-doesnt-matter-yet-another.html
2560x3840 is 9.8 megapixels. So as long as they're well-focused, and don't require very much cropping at all, you'll be fine.
https://www.damiensymonds.net/2014/03/how-aggressively-can-i-crop.html
Do NOT use this shit. Photoshop does a perfectly good job.
Only just. What size brush were you using to mask around the handles; and at what zoom were you viewing when doing so?
(Hint: The answers should be (1) No bigger than 6px, and (2) No less than 400%.)
Download PSD
I experimented with lots of blend modes before deciding that Linear Light looked best. https://www.damiensymonds.net/2011/06/sometimes-you-get-lucky.html
The "Levels 1" layer isn't part of the edit, it's just the layer I used to check that I'd completely blackened the silhouette.
The Pattern Fill Layer is some noise to prevent banding: https://www.damiensymonds.net/tut_noise.html