help at playing necrons better

Hey so I'm quite new to 40k in general but i got into it mid 2021 and started playing with a friend via the indomitus set (me being the necrons obviously). With this we expanded our armies and now play with a variety of different builds. However i am constantly losing. A big part is due to poor tactical decisions. I play custom dynesty eternal conquers 6" movement ect. I usually have large blobs of warriors, lychguard, sorpekhs and CCB with technos and chronos. I used to run doomstalkers but im now more inclined to use LHD instead. My friend plays iron hands predominently. Here are some questions though.

1. How many grenades can a unit use. I get wiped by frag grenades getting 60 shots. I read somwhere that a unit can only use 1 grenade. Is this true?

2. Does reanimation occur before or after consolidate?

3. What are some good combo strategems (i mainly like Disintergration cpacitors & relentless onslaught)

4. any tips against iron hands and playing necrons better in general.

5. If i took a objective and my oponent then has equal models, does the objective become neither players or remain mine until he has "taken" the objective.

6. Redemptors are a killer, any tips? i swear i can never efficiently take these out. doomstalkers are to swingy but they IMO are much cooler then LHD (even if i think LHD is better).

EDIT: I asked my friend and I misheard he used a aggressor squad with the fragstorm grenade launcher. I just misheard and thought he said he threw grenades with bladeguard vets.