Clicking or 'snapping' hips are quite common and often not actually a problem. If there is no pain and you have good movement in the hip then I wouldn't worry too much, especially if it doesn't affect your running.
There are a few reasons for it, most common are the ITB or Psoas tendon. If the clicking is on the outside of the hip then it's more likely to be the ITB if it's in the front of the hip and into the groin then the Psoas tendon is more likely. The theory is that the clicking is the tendon moving over a bony prominence. A less common cause is a structure within the hip joint called the labrum.
If it persists and causes pain then seek a medical opinion. If not I wouldn't worry too much. Stretching probably won't change it though.
Achilles tendinopathy is often persistent and difficult to treat, however with the right management it can improve. I agree with PSC, calf strength is very important. Recent research now suggests that muscle strength may be one of the key areas in tendinopathy.
So how do you progress? Firstly you need to seek out an experienced physio who can do a thorough assessment and determine if it is Achilles tendinopathy and whether it's insertional (where the tendon attaches to the heel bone) or mid-portion (in the middle of the tendon). This is important as these two different types of tendinopathy have different treatments.
Secondly you need to address factors that contribute to the injury. Your weight may well be an issue and so losing weight is likely to help. Also people often do exercises or use treatments that make things worse, particularly stretching. This may sound odd but I wouldn't stretch your calf muscles as this is unlikely to help in the long term. Stretching mainly effects the tendon rather than the muscle, you want a strong, fairly inflexible tendon that can handle the force involved in running, stretching won't help this.
Crucially you need to improve the muscle and tendon's ability to handle load. This can be achieved by strengthening the 2 calf muscles (gastroc and soleus). For years people have focussed just on 'heel drops' on the edge of the step but more recent research shows that calf strengthening (e.g. simple calf raises) can be very effective if a high load is used. By high load I mean doing single leg calf raises lifting your own body weight plus around 10-20kg extra (held in a backpack).
The problem is this is often painful to do initially so I recommend a graded build up. Start with 'isometrics' on 2 legs. Do a 2 leg calf raise but hold it for 30 seconds. Repeat 4 times and do this twice per day. When this gets easy progress to doing this on 1 leg. Isometrics really help settle pain and start gentle loading.
Next up progress to 10-15 calf raises, this time without a hold. When you can do 3 sets of 15 just on your weaker leg start to add extra weight and gradually build up. This extra weight stimulates the tendon to recover - it doesn't damage it.
Ideally you want to do 2 types of calf raise - straight knee (to target gastroc) and with the knee flexed to around 30 degrees (to target soleus). Do around 3 sets of 15 reps of each exercise every other day and give it time. Tendon's take around 3 months to adapt to loading you need to keep strength work up for at least this length of time. It doesn't take long to do the exercises and it is worth it.
I hope that helps and makes some sense!
Let me know if you have any questions, also if you let me know where you're based I can try and recommend a good physio near you.
I agree with Seren Nos, it's about seeing how the tendon responds to the exercise. See how it feels at the time and look out for any reaction for 24-48 hrs after.
It does depend a bit on how irritable your achilles problem is, where the pain is and how acute it is. If it's a new episode and is easily aggravated then you may need to be careful with the cross trainer. Also if it's an insertional tendinopathy (pain where the tendon inserts into the heel bone) it is more likely to be aggravated than a mid-tendon issue.
Are you seeing someone about this? If you want more info let me know, I have some achilles articles you might find useful.