Grey Engines - Telepathy

Telepathic communication between telepaths, without technological aid, has a range dependant on the strength of the strongest telepath, but not usually much more than a mile.
Telepathic communications between a telepath and a non-telepath is more limited, since the telepath has to do all the work, so the range is usually around half as much as they could normally reach without straining them.
Privacy is relatively easily maintained for such communications (and required by etiquette where other telepaths are about). They can be intercepted by others, but it requires significant skill to do so undetected. Long distance communications assisted by braintech can be monitored by the brain trust, but they generally don't do so (etiquette, again).

Probing other minds is a serious breach of etiquette (outside of law enforcement, where it's still serious, and they have braintech support), and is difficult against other telepaths, anyway, since they have defences.
It first requires the telepath to make Contact with the target mind, so has the same range as standard communications, but unless they do so with delicacy enough to not alert the target, or if the target is willing, the target's defences should throw up enough static to make the search incapable of finding anything, anyway.
Probing the memories of another mind is a hard task even without encountering defences, and few have the gift to do it well (and safely, without risk of damaging the mind and memories). For law enforcement purposes, artificial minds specially designed for the task are used, usually being specially designed for the target, but there are heavy restrictions on when they may be used.

Mind Location
Telepaths can locate all minds near to them with a light scan, or search for a particular mind within range. The range of such scans is usually around twice as far as they can communicate. Locating minds does not require any form of contact between them, and the target may not be aware anyone is detecting them in this manner unless they happen to look for such.
Hiding from such searches is possible with concentration, but prevents the telepath using any other active form of telepathy at the time.

While theoretically possible for a telepath to influence another mind, against another telepath it would require such a disparity of psychic ability that it has yet to be really tried. The best results would require that the target mind be unaware of the initial intrusion.

Psychic attacks other than in self-defence are a serious taboo in society (even though most telepaths can protect themselves from serious damage), and are considered a serious crime. They are practiced by the military and police against specially constructed brains, and the latter force has developed low-damage subdual techniques which are only used when absolutely necessary.

Telepaths can defend themselves against most forms of telepathic communication, detection, intrusion, and attack if they wish. It depends on the relative strengths of the two telepaths how successful the defence would be, but other than avoiding detection, most other forms would cause enough static as to make the attempted contact have little effect.

Apart from general psychic strength, which tends not to vary to a great degree except in exceptional circumstances, individual telepaths tend to be, or become through training, stronger in some areas than others. There can be differences in range, accuracy, depth (amount of information conveyed in a message), delicacy (how gentle their contact is, and how likely to be noticed), and multi-tasking. If their role requires strength in a particular area then their natural aptitude will be enhanced through training.

Non-human Contact
Telepathic connections with non-humans is harder than with humans, but is possible. With animals the trouble comes in conforming to the simpler thought patterns, but giving simple commands is fairly easy, and unless the telepath is particularly clumsy (in which case they may spook the target) animals are often quick to obey, taking it as their own thoughts.
Contact with aliens can be harder dependant on the mental make-up of the species, and how similar they are to the telepath. Communicating with telepathic aliens involves synchronizing the individual thought processes, but while such communications may be formal and require concentration, they can be deeper and more efficient than trying to translate verbal communications, and become easier with familiarity.
Contact with non-telepathic aliens can take more work as the translation work is all being done by the telepath, and unless care is taken making contact, the target may react strongly to the mental intrusion, making them more resistant, and probably hostile. Intrusive scans and influencing their mind can be hampered by the differing though processes, but blunt attacks are not usually less effective.

Artificial Amplification
Braintech allows a telepath's natural abilities to be amplified, but unless they have mobile braintech devices, which is rare, enhancing any ability other than communications over the public braintech grid requires getting it cleared by the brain trust first, and most legal activities the brain trust would do on the telepath's behalf, rather than aiding them in doing.