I want truth about powered and unpowered USB 3.0 hubs, external HDD, SSD power needs

[virtuality]

I'm in the market of modern ultrabook with not many ports (a MacBook Air, in fact). I thought it would be a cool idea to add the perfect USB 3.0 hub (with Ethernet) for conveniently adding peripherals.

2 concerns:

1#

- Do I need a powered USB hub, or an unpowered will suffice? The latter travels better, which is a plus. To add insult to injury the market confuses me with the following options:
-- 3 (or 4) port hub, unpowered
-- 3 (or 4) port hub, powered
-- 6 (or 7) port hub, unpowered
-- 6 (or 7) port hub, powered
Basically all options. 3 ports + Ethernet will suffice.

Now I know if I were to add external 3.5" drives, I'd probably need external power. But I will not need to attach 3.5" drives.

Devices I plan to add:
- 2.5" HDD
- 2.5" SSD
- USB flash drive
- SD card via USB adapter
- Ethernet

I will also need a SATA to USB 3.0 adapter. Which further confuses me by having an optional power cable to it (sample image via Google Image Search):

So I might or might not need the extra power for the SATA 2.5" HDD or SSD, who knows? Depending whether I connect it to the notebook directly, or to the hub, being it powered or unpowered itself?

Reviews are also all over the place stating this particular hub powers the particular devices are add, this particular hub does not power the different set of devices I add.

2#

Most of these ports come with a non-removable ~50 cm USB 3.0 cable connecting it to the notebook. I prefer it to be connected via a 2 m long USB 3.0 extension cable altogether. so, if there is a 0.5 m non-removable cable, I need an extra 1.5 USB 3.0 extension. But how will it affect the power reaching from the notebook to the hub? Will the extension affect whether I need a powered or unpowered hub?

 

[virtuality]

Related side-note.

 

[Cerb]

1 USB 2.0: 500mA@5V, or 2.5W.
2 USB 2.0: 1A@5V, or 5W.
1 USB 3.0: 2A@5V, or 10W (high exists, but this you can definitely get).

An unpowered USB 3.0 hub would be fine for most things, but if you're hanging multiple HDDs off of it, or use it as a charger, you might want a powered one, instead. Powered USB hubs always treat external power as optional, IME, so one like this should work fine without the adapter attached, unless you end up needing it.

For USB to SATA, just get a USB 3.0 one, with no external power (I don't know if the external power is really optional on the smaller ones - my USB 2.0 ones required it, FI). Example. You're not going to run across a 2.5" SSD that will use even 5W.

Personally, I'd get one of the $20-30 Inatek, Anker, or Satechi hubs with GbE, and then only buy any other if that one failed to work well enough, one day.