Q: When I import photos into my Macbook Air, I delete the photo off my iOS device, but then the photos disappear from my computer as well. How do I fix this issue?

If you enabled iCloud Photo Library, then everything gets synced with everything else. Deleting images will delete them from iCloud and all other devices with iCPL enabled.

Deleted pictures are kept for 39 days in Recently Deleted a,bum. You can recover them from there.

https://help.apple.com/photos/mac/1.0/?lang=en

http://www.imore.com/how-use-icloud-photo-library-ultimate-guide

If your Mac and iPhone are both using iCloud Photo Library, then deleting something for your iPhone will also delete it from iCloud and subsequently, your Mac.  First step here would be to recover your photos.  Go to iCloud.com and look at your deleted album under photos.  Once you have recovered the photos, you may want to turn off iCloud Photo Library on one or both of your devices to keep them form syncing, or simply export your photos you wish to archive out of the Photos app on your Mac, into another folder.

iCloud Photo Library FAQ - Apple Support

So exactly what is the issue you are having - you list two totally different ones

1

When I import photos into my Macbook Air, I delete the photo off my iOS device, but then the photos disappear from my computer as well. How do I fix this issue?

This is not an issue and there is no fix because there is no issue - you are using iCloud Photo Library and that is exactly how it works  - it is a syncing service and every change made on any device (additions, deletion or edit) is made on all devices - for devices with limited storage you use optimized photos  --  you can not "fix" something that is working correctly  exactly as documented

2

I'm having trouble sending photos from the icloud on my iOS device, how can I fix this?

For this we need more details - what are your iCloud setting and status on each device? The most likely cause is that everything is not yet uploaded and nothing is downloaded until the upload is complete - but until you give us details we are only guessing

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