This is the one Moondog Wily uses and I think this is the one that will work best for me too.
Good enough for Pete Thorn.
Good enough for my simple needs.
When the Focusrite arrives should I just return it? To be honest, if I don't need it I'd like to put the money towards something else I DO need.
I think you will be happy with the Tascam Model 12. It is a mix of old school (sliders, knobs) and new school technology (digital interface, bluetooth capabilities, built in effects, SD card recording built into board). He mentions in the video that these are 60mm sliders rather than the 100mm sliders László mentioned above. I have never had an issue with them, but if you are used to 100mm sliders, I can understand some of the issues some may have with these. Considering what you are trying to do (vocal, back up vocal, guitar and percussion) and the quality level you are expecting (home studio), I personally think you will be fine (and as László said, Thorn is not using this for his projects).
Thorn does mention that he is NOT using it as an interface, but is instead recording directly to the SD Card. I wish he would have covered some of the connection to the DAW, but it is not difficult and I can not imagine the difference in sound quality would be anything you will be picking up on if any even exists. I have used it both ways and have been happy with the results of each, but have never done any direct comparisons.
You can return the Scarlett 18i8 unopened! It will be of no use to you considering the I/O capabilities of this board. Would the 18i8 sound slightly better to some professionals? Perhaps. Will it make a difference in what you are trying to do? I would say no but could not say for sure unless I were to compare them side by side with a nice set of test equipment in addition to my ears.
If you are going to choose to use the on board recorder, you will need to buy and SD card as the Model 12 does not come with one (at least mine did not). If you are not going to record on the board itself, then you do not need an SD card. As mentioned above, I have used it this way and was happy with the results, especially when I would have my rack in a room away from my main computer. The SD card you will need should be Class 10 or greater. Let me know if you need some links to SD cards to consider.
Not sure what USB inputs your Lennovo has, but if it is all USB C (some modern computers are going this route), then you will either need a USB C to USB C cable or a USB A to USB C adapter to fit onto the supplied cable. If you have USB A inputs on your Lennovo, you should be all set and not need any additional cables. The unit will come with a USB A to USB C cable.
This unit will give you a LOT of options for both input and output. For example, without even hooking up to a computer, you will be able to output to two pair of headphones, each with their own volume knobs, main out and aux out to run to speakers or PA (each with their own slider for output level). Hook it up to a computer and you then have all those options PLUS all channels going to the computer, and then you could do what you please with the output from the computer (additional headphones, speakers, etc.). Note that input channels 11 and 12 are from a 1/8" stereo input jack, so utilizing those channels is difficult from 1/4" or XLR cables unless you have the necessary adapters, but you should not need them.
Give a call or write with any questions, happy to help ;~))
Congrats and cheers! Looking forward to hearing your material!!!