Viruses are "on the edge of life ". They infect the cells and use it for multiplication of themselves but other than that do they do anything else like "eat food" like an amoeba or move on their own like Euglena ? Do they share any other characteristics with living things other than being able to reproduce ?
Skirting the Question's fringe, and too long for a comment:
On symbiosis with viruses, from some science magazine:
Most viruses are harmful, but some viruses have a mutually beneficial relationship with their hosts. A lot of viruses help their hosts by attacking their competition. For example, the hepatitis G virus slows down the growth of HIV, the virus that causes AIDS, in humans. Bacteria grow viruses inside their cells and infect competitors with those viruses. Other viruses are needed for their host's physical development. When wasps lay eggs inside other insects, their eggs are equipped with viruses. These viruses fight off the infected insect's defenses and guarantee the eggs' survival.
They infect the cells and use it for multiplication of themselves but other than that do they do anything else like "eat food" like an amoeba or move on their own like Euglena ? Do they share any other characteristics with living things other than being able to reproduce ?
No, viruses are not considered living entities, because they do not extract energy from the environment (aka eating) and do not do any active work like moving or constructing themselves. They entirely rely for these functions on their hosts or random influences (like being carried by air in droplets).
Maximum of what some viruses are known to do are attaching to a cell and a simple one-time syringe-like movement to penetrate it.
Part of ecosystem
Being obligatory parazites, viruses certainly play a role as a part of their ecosystem: e.g., limiting the population of their hosts or even being in symbiosis with them (as pointed in the other answer). It is necessary to note in this respect that a "successful" virus is not the one that causes the maximum damage to its host, but rather the one that most efficiently uses the host to replicate and spread itself. This drives viruses towards co-existence with their hosts, since the extinction of the host would also mean the extinction of the virus.
It has been argued that viruses play a role in horizontal gene transfer, gene duplication, etc. Some parts of mammalian genomes are identified as deactivated ancient viruses, which continue producing proteins essential for the functioning of the host organism. See, e.g., here.