I dunno about that but I've been using my 10kg washer with normal 13A wall socket for probably 10 years with no problem

Cheap extension cable use cable probably just enough to carry the max current. Buy one with thick cable. Anyway, it is no harm to buy higher rating extension. There is benefit when doing so. The 3 pin plug wire inside the wall can carry more than 20A current actually even though the MCB is rated at 20A.

If you run wire near its max current load for long period of time, the wire will get warm. Over time the insulator might become hardened and fail. A good socket will have firm contact to plug pin. If the contact is loose, then resistance at contact point will be high. Running high current through this poor contact, the resistance converts current to heat. This is the normal cause of fire on extension wire and it is also the same reason even for wall socket. It is always good to have headroom (extra buffer) for for current flow.

Exactly, but I'm worried hence wanna ask to double confirm

1) Powder is more cost effective but liquid allow spot treatment of stains (rub undiluted detergent on stain before washing). Powder need to follow instructions to put in detergent+softener box. (See reason why in (2) below)

2) Liquid can pour direct in drum. DO NOT PUT POWDER DIRECT IN DRUM because it won't have enough time to dissolve properly if don't put in the detergent box.
- For concentrated detergent, half the recommended dose on the packaging is enough if clothes are not too sweaty/dirty.
- Too much detergent / use powder direct in drum will cause clothes residue that look like lint or white stains.

3) Clean lint filter of the machine and do regular cleaning cycle. Follow LG instructions: https://www.lg.com/us/support/video-tutoria...-20150712778997