Biorb 60 Second Hand

Heaters - the guideline is 1 watt per litre so 50w is a bit underpowered for 60 litres. It also depends on the make; as with all things in life you get what you pay for, generally speaking.
If the heater is set to max and it won't keep the water warm enough, it sounds a though you need a new one. I'd go for a 100w heater with a 60 litre tank. Heaters are rarely accurately calibrated, so they rarely heat the water to the exact temp you set, but it's not this case with your newly acquired one as it is set to max.

Filter - keeping the media wet ensures a better survival rate, but we now know that the bacteria can survive if the media is just damp because they are embedded in the biofilm. The thing to do is set everything up and add a 3ppm dose of ammonia. If you test 24 hours later and find zero ammonia and nitrite, you know enough bacteria survived and it is safe to get fish. If there is still some amm and/or nit after 24 hours, you need to continue with a fishless cycle or get a very few fish (if there are only small readings next day) and stock slowly as for a fish-in cycle. Though in the latter case, do a water change to get rid of the trace before adding your few fish.

You can find ammonia in some branches of homebase, in the cleaning section. Failing that, Jeyes Kleen Off Household Ammonia from amazon/ebay, though I got mine from my local diy shop. Be careful as there are several products in the Kleen Off range in identical looking bottles and you don't want to get the wrong one! I have heard of someone who tried to cycle using drain cleaner......

You may find that you do have some bacteria still alive in the media. In this case adding ammonia will let you know if there are enough of them to get fish or if you need to grow more bacteria. Things could well go a lot faster than a fishless cycle with brand new media. With the biorb, the main biological media is the substrate, those rough looking lumps. I understand there is also a box which contains carbon and a sponge - there will be some bacteria in there too, but that is mainly for mechanical (sponge) and chemical (carbon) filtration.

Once the ammonia arrives, add enough to get 3ppm. If it's Jeyes, it won't say on the bottle but I emailed them when I got mine and they said it's 9.5%. Your biorb will most likely hold less than 60 litres (most tanks hold less than they say it does). I would add 1.5ml ammonia and check the actual reading after half an hour-ish to allow it to mix. If it is somewhere between 2 and 4, that's fine. Check it, and nitrite after 24 hours. If both are zero there are enough bacteria for fish. Add 0.5ml ammonia every 2 or 3 days till you get fish to keep the bacteria fed.
If one or other are not zero after 24 hours, proceed with a fishless cycle. It should go quite quickly even if there are only a few live bacteria left - it's getting them started that's the long bit.

There are two schools of thought. If you leave in with nothing but the filter media in there (the rocks on the bottom for a biorb) you won't get algae growing on the decor. But if you don't put decor in, you won't get biofilm and bacteria growing on that - though if you put them in and you get algae, you'll have to scrub it off and that'll scrub off the biofilm too. I don't think there is a right or wrong way to do it, just personal preference. I just put sand in the bottom when I cycled a tank last year as I didn't mind having an empty tank. I put the decor in after.

When you add the next 3ppm dose, I would add just 1ml rather than 1.5ml. The problem with adding too much ammonia is that it makes too much nitrite and too much nitrite can stall the cycle. 1ppm ammonia is converted to ~2.5ppm nitrite; 15ppm nitrite is when it stalls the cycle, which is made by 6ppm ammonia. So adding over 6ppm ammonia in total before the nitrite eaters have started growing can lead to over the stall amount of ammonia.

If the old stuff looks OK, you could still use it. It's if it looks cracked, dirty or clogged that would definitely need replacing.

If you'd prefer to get all new, now is the time to do it.

When I did a fishless cycle last year it took 13 days before anything happened. And it can take longer than that. Fishless cycling is a lesson in patience! So long as your ammonia reading is no higher than 4, you just need to wait, I'm afraid.

This is the first time ammonia has dropped?

If this is the case, you meet the ammonia below 0.5 and nitrite above 2.0 criteria and you are on point 6 of my 'How To' thread; add a 3ppm dose of ammonia and start testing every other day.
You will then wait to get 2 consecutive tests (two tests with a day of not testing between) where ammonia is zero on both days (point 8 of the How To thread). Don't add any more ammonia until you get these two zero ammonia readings.