There are several heroes who have skills that add 0.5% DPS to Click damage. These make click damage scale with DPS damage and aren't one time increases. Once you have these unlocked, it's pretty useless to upgrade Cid past unlocking Click Storm, except to reach tiers for Hero Soul.
An ancient has a special stat attached to it which you can level up with hero souls. Depending on the stat, such as extra DPS or extra gold drops, it will have a maximum level cap, or it can go on infinitely. Ancients will stay with you through ascensions like gilded heroes.
Totally recommend Vaagur, the Ancient of Impatience first. You want to fire Dark Ritual as often as possible. I recommend this one first, because the more ancients you have opened, the more hero souls it costs to buy another separate one.
Click the Eye of Providence tab (the fourth one with the eye in the triangle) to get to the Ancients menu. Ancients are just buffs that last through ascension.
A typ to get hero souls is, everytime if u upgrade 2000 Hero levels, you will rewarded with 1 Herosoul. It means, if you upgrade 10000 times hero's you will get 5 Hero Souls.
In short, ascension is done in order to get hero souls. I haven't 100% figured it out myself, but I think you have to get hero souls to get ancients which help you advance further than you can without them. I think at level 140 you have to ascend or else you can't beat the boss and move on.
When you ascend you start over at level one and lose all your heroes. I'm not sure if you lose your dps and click damage though.
Achievements are kept throughout, and it's a good idea to ascend just to grab those achievements while you build up your hero soul count to tackle the harshness that is level 101-200. You'll find that with extra hero souls fighting early bosses will be pretty quick, and you can rack up the achievements based on killing bosses by leaving it on. Bosses give you more gold than monsters which are four zones ahead of it, but people often don't leave it on a boss stage because the rate of gold farming is slow. With more hero souls, you don't have to worry about this.
The hard ones you could translate to "time consuming".
Well said ^^
is it better to ascend as soon as possible to leave it until later on? should i spend my soul shards or save them until after I have ascended?
I personally think it's better to ascend when you get as many Hero Souls as possible. (about 10 is a good number to ascend) You can ascend earlier, but there is really no use for it because you need the hero souls to move further anyway.
And spending the shards you get from defeating bosses before you've ascended is up to you. When you do it doesn't really matter, but I'd suggest ASAP so you can have the effects of the ancient for longer.