When my fella & I mess around, we use a lot of vibrations from our other toys because it does get us both going during sex, but I'm a little worried about anything actually entering. 
So, I've got a few questions if possible!
1. What lube would be best to use for them?
2. How easy are they to clean after?
3. Are they really as flexible as the reviews are saying?
1) It’s gotta be something water-based. I’d recommend something like Lovehoney’s own brand anal lubricant Discover as it’s thicker than regular water based lubes and will provide some additional comfort during backdoor sessions.
2) The specific ones linked above? Not as easy as something made from silicone, which is a material I’d recommend for anal play, particularly if the toy might be used by both of you at some point. Silicone is hypoallergenic whereas the other material is not. Hypoallergenic surfaces are always much easier to clean than the alternatives in our experience. Regarding cleaning of the actual beaded design - they’re fairly simple to clean. Just pay attention to the spaces between the beads whilst rinsing to ensure all residue is removed.
Couple of beginner friendly examples of silicone alternatives:
3) I haven’t tried those specific ones, but generally most of the beginner anal toys on here are are flexible to allow for comfort, easy insertion/removal and good angling. I have got the pair that I listed above and those are flexible, but not flexible enough that they’re flopping all over the place and won’t stay inserted. :-)
I would definitely agree with NatandTom about getting silicone ones, particularly if you are planning to share the beads.
As for lube, a good quality water based, anal specific lube is what you should go for as it will be compartable with all toys. Just remember to use plenty and be prepared to reapply if you keep them in for a fair while.
NatAndTom, the 50 shades silicone ones look really good, we'll possibly be purchasing those ones, as for a water based lube, we're looking at this https://www.lovehoney.co.uk/product.cfm?p=31585
Out of curiosity then, whats the difference in materials being more hygenic than the other?
Out of curiosity then, whats the difference in materials being more hygenic than the other?
Silicone, glass and steel are non-porous, they won't absorb smells, bacteria or anything else which makes it a lot easier to make sure they are properly cleaned. Over time it is possible for other materials to absorb bacteria, it's recommended you use a condom with them, check the toy for discolouration regularly and replace after a while (I think I read about 1 year but I might be wrong). Of course this becomes even more relevant if a toy is used anally.
I use the Discover lube NatandTom recommended and you've linked but I buy the bigger bottle, it's easy to get through quite a bit when you first start.
I also have the second beads NatandTom have linked, they were my first and I'd probably still say my favourite, they are a different and really interesting shape although you don't get the 'pop' of each being inserted or taken out as much as others because there not much of a gap between them.