All my bitcoins are currently on my Ledger hardware wallet. I have many different amounts ranging from 0.01 - 0.3 per address. Probably about 50 different transactions. Is it advisable and necessary to consolidate these amounts?
Yes. The reason being if you need to make a transaction that uses lots of different coins from your Ledger, and fees are high at the time, you will end up paying a lot. If you consolidate them all in to one when fees are cheap, it will save you on fees down the line.
All addresses are segwit - starting with 3.
You can move from all these addresses to any other kind of address you like. I would probably stick with another nested SegWit "3" address since that's what you are currently using anyway.
From reading the topic it was suggested that I use Electrum for the consolidation.
Lots of people use Electrum with their Ledger because it is easy to do so, and Electrum has more functionality than Ledger Live. You don't
have to, however, and can still consolidate all your coins with Ledger Live if you wish.
From what I can see the Fees now are pretty high so using 1-2 Byte/Sat would not work right now?
Not immediately. But the whole point of consolidating is to pay a small fee when you are not in hurry. I would always consolidate with a low fee of around 1-2 sat/vbyte, and just be prepared to wait a couple of days for it to confirm.
Do I need to move my bitcoins from Ledger to a new address on Electrum or can I sync those two together and do the consolidation on Electrum?
You don't need to move coins from Ledger to Electrum. If you wish to use Electrum, first download it from electrum.org (make sure not to download from any other site, there are a lot of fake electrum sites out there). To be extra safe, you can verify your download following the instructions here:
https://bitcoinelectrum.com/how-to-verify-your-electrum-download/. Once Electrum is installed, it is very easy to open your Ledger wallet in Electrum by following the instructions here:
https://support.ledger.com/hc/en-us/articles/115005161925-Set-up-and-use-Electrum/. By following these steps, you essentially use Electrum to open your Ledger, in the same way you currently use Ledger Live (I assume) to open your Ledger. The coins never need to move to do this.
I have no experience calculating size, inputs, outputs, can someone please tell me how to do this properly as I have never done that before?
Essentially, all you need to do is send all the coins in your wallet to a new address in your wallet, and make sure you set very low fees. Ledger Live or Electrum will do everything else for you.