Safari tabs no longer syncing & Handoff option missing, plus Bluetooth not connecting

I saw an earlier thread about Tab syncing only working with Handoff enabled. However, Handoff has mysteriously disappeared from both my iMac & Macbook Pro (both late 2009) running El Capitan. It was there before and now it's gone as of fairly recently. As in a matter of months, maybe late last year as I was too overwhelmed (aka irritable) to deal with all the problems across my four Apple devices and was about to scrap them all to switch to the "dark side" (Windows/Android) after too many issues. But I hate to give up just yet.

Safari tabs previously synced across all my devices including iPad 4 and iPhone 6 Plus, both on latest updates. What gives?

Also, I read that Bluetooth must be on for Handoff, and hence tab syncing, to work. Is this true?

I don't remember it being this complicated all these years I've had these devices.

But if so, I'm trying to sync all four devices and they won't all connect at once. The two computers don't even want to sync at all. Laptop now just has an x to delete. No sync button.

Also, I've already reset all the various settings, rebooted, hard resets, etc. to no avail on every device.

I'd wipe them all out and reload afresh (probably need to) but I'm missing original software, namely CS5! The iMac is a clone of the orig. Macbook Pro as it is. Ack. I'm on borrowed time but any ideas how to salvage these would be most appreciated. Am I missing something obvious?

On a side note: if I suck it up and upgrade to new devices, is all the syncing just going to break still anyway? I'm on my 3rd iPhone 6 Plus and they've all been defective in various ways. Been hesitant questioning reliability across the board. Just want a couple things that WORK well! Not a techie guru.