@jmaunsell Generally best to get adjustable length with flick lock style latches rather than the twist kind which are more problematic to maintain. You definable want then to be "collapsible" for transport. (You have to check them on a plane)
There is a particular technique to using hiking poles that makes them more effective...so find a video. Basically your hands comes up through the loop to lightly grip the handle over the loop so your weight is supported by the loop. You may need to adjust the loop length accordingly. In normal use you do not grip the handle tightly.
Cork grips are generally considered more comfortable. I have foam and they work ok. Hard plastic is only ok if you wear gloves imo...generally these days I wear sun gloves when hiking because hiking poles put your hands in a very exposed position sun wise.
Buy quality because you are putting your weight on it and if it fails you could fall and injury yourself.
Adjustable is better because you generally want shorter poles going up hill and longer going down and you may want to have one longer than the other on a traverse... and they are more useful for other things like pitching trekking pole tents...However mostly...once I have the length I like I don't tend to change it much while hiking but just change my grip...poles that have additional grip down the shaft blow the "handle" are preferred for that reason.
I have shock absorbing poles but I don't think it is necessary and it adds weight and cost. We carry rubber tips for sections of slick rock and paved road and also for transport.
10 years is a long time but Black Diamond have historically had replacement parts. The carbide tips do wear out with use and BD tips are fairly easy to get and replace. They have two styles...a screw in tip and a full replacement which has to be heated to remove. I have replaced the latter myself. I have also replace the lower pole section when it got bent which is not uncommon.
Personally I prefer aluminum over carbon fiber because aluminum bends and can often be recovered at least for the rest of the hike so long as it doesn't fold where carbon fiber will shatter if it breaks.
You can get fixed length Z folding poles but you need to know the correct length...generally from just above your elbow to the floor. If it is just for walking and not backpacking, Black Diamond make some very lightweight ones in this style. I am skeptical if that the stretchy plastic thing that allows them to "Z" will last 10 years though.