1. Can we do wudhu with the sea or ocean water?
2. Can we use sea or ocean water which is salty in nature to purify things that come into contact with Najasah.
3. If pure water that is available is Qaleel /less than Kur; how much is needed to purify najasah. For example, to wash off urine how much water is required in quantitative measurement?
4. If a carpet that is attached to the floorboard becomes najis then how can it be purified without sun exposure? How much water is required to purify the area?
5. If a halal animal consumes Haram and is slaughtered in a halal way, can it be consumed? E.g. A camel if it ate Haram it's sweat is considered najis does that mean we cannot eat the meat of that camel if it is slaughtered? Can we consume the milk of the camel?

1- Yes.
2- Yes
3- One time only, provided the urine is dry. For clothes, you need two times, with a squeeze in between.
4- If the najassat is urine, 2 times with a squeeze in between.
5- If it was eating human outlet regularly, then yes, it is haram.