Which of these two feats best supports my Cleric / Druid multiclass character?

Question

I have a character that I have created with DnDBeyond.

The Character is currently a level 3 circle of the moon Druid and Level 1 disciple of life Cleric.

I'm our party's healer so I have tried to buff my PC's healing abilities but I am also trying to amass lots of various spells.

I can cast druid spells and cleric spells with my Wisdom but I also have a spell book that I found.

Our next session is this Friday so I am trying to plan my PC's future.
On my next Druid level I will be able to take a feat and I'm torn between War Caster and Ritual Caster (Wizard).

War Caster will be helpful all around for my character.
Our GM has pretty much left me alone during combat since I haven't been able to do much except heal and throw small spells from a distance. But now that I have Bless he's started taking shots at me to disrupt my concentration. War Caster will be really helpful now that Bless, Guiding Bolt and Wild Shape have started making me more of a threat on the battle field.

Ritual Caster (Wizard) Will allow me to use Wizard spells.
I know that I have to use the Spell Book to cast the spells and I have to use intelligence rather than Wisdom when casting out of the spell book but here are my questions.

1. Can I add any of my Druid or Cleric Spells to the Spell Book?
2. Can I then create Spell Scrolls of my Druid and Cleric Spells?
3. Do I need a Spell Book at all to make a spell scroll? ex. Could I make a level 1 Cure Wounds spell scroll to give to my party members?
4. Can my Druid use a spell book without taking the ritual caster feat and just use intelligence as the spell casting ability instead of wisdom?

Answer 1

1) You can't copy Druid or Cleric spells into a spell book.

From Player's Handbook (page 114, Your Spellbook sidebar):

Copying a Spell into the Book. When you find a wizard spell of 1st level or higher, you can add it to your spellbook if it is of a level for which you have spell slots and if you can spare the time to decipher and copy it.

Emphasis mine. A wizard's spellbook can only contain wizard spells. Cure Wounds, Goodberry, etc. are not wizard spells, so you can't copy them in. Note that some spells that you get as a cleric, such as Protection from Evil/Good, are also on the wizard spell list. You can't copy these in unless you have a scroll of that spell, since even though that spell is on the wizard list, you know it as a cleric spell.

2 & 3) You can scribe a scroll of any spell you know.

The rules for scribing spell scrolls are in Xanathar's Guide to Everything, page 133. The only requirements are that you have money for the materials, training in Arcana, and any expensive material components the spell requires. You could do all of this right now, even without Ritual Caster.

Note that these rules are technically optional, and there are no rules for creating spell scrolls in the core books. Be sure to ask your DM how he wants to handle creating spell scrolls.

4) You can't use the spellbook as a druid or cleric.

Druids and Clerics do have Ritual Casting, however they only allow you to cast druid and cleric ritual spells that you have prepared. The only way for you to use the spellbook would be to take levels in Wizard, at which point you could make it your spellbook.

Note that even with the Ritual Caster feat, you can't actually use the spellbook. Instead, you would need to create your own ritual book, and then copy the spells from the spellbook you found into your ritual book, paying the costs as usual. However if you ask your DM they may allow you to use the spellbook you found as your ritual book.