I'll assume you are a newer Whm, and possibly a newer player as well.
Early on, your biggest stat boost you will want is Mp, you'll learn early on, then when a Whm runs out of Mp, things start to fall apart.
Tied in with wanting MP, is HMP gear, or MP while resting gear. There is a Handy level 10 Wand you can get off an NM in Saruta, called Pilgrim Wand, you'll use this every time you rest until level 51, unless you get the crafted version at level 34. It has HMP +2 on it, which means when you sit to rest, each tick will restore an Additional 2 Mp.
Also in line with this are cookies, your Food of choice. Cookies; Ginger, Wizard, Cinna, Coin, Acorn (forget the last kind) all have a HMP + trait to them. Ginger are Easy to find and quite cheap, costing about 12 gil each. They offer HMP +5. There are useable at all levels, and for much of your WHm career, you'll want to use these of Wizard cookies (wizard offers HMP +7)
However, HMP is ONLY good while you are resting, so keeping that gear on at all times is unneccessary and somewhatwasteful.
Likewise with MP gear, if at max, you have 200 Mp, once you use up 50 Mp, the gear you have pushing you up to a max of 200 is useless until you sit to rest.
This is where stat and situational gear comes into place. Mnd is the main stat you want to look at as a whm. Mnd will help with your enfeebles as well as raise your cures to their cost caps faster, and eventually Break the soft caps (paired with Healing Skill and Vit, but Mnd is the largest contributor)
Since Most Wands that offer Mnd + stats also offer Int + stats i'll mention Int. As a Whm, its not As useful as some other stats, however it Can help your Sj a bit. If you have other enfeebles from Blm or Rdm SJ like Blind, poison, bind, those are Int based Enfeebles. While Slow, Para and Silence are Mnd based.
Lastly you'll want to look at defense. In a perfect world you'd never get hit, but thats not the case. A stary hit will land on you occasionally or an AoE will hit you, having Any defense is better than none.
So basic Stat order; MP>HMP>MND>ALL OTHER STATS>DEF.
However you'll want to be careful with Convert HP to MP gear, since it can dractically lower your Hp and survival potential.
As for SJs, early on, from 1-30, Blm is a Very good Sub Job. You'll want to take this to 37 at some point because its a situational SJ. If you ever teleport for gil, you'll need Blm.
Summoner is also a Situational SJ. However much less situational than Blm. At level 50 /Smn will offer Auto-refresh which is a Nice Draw, but thats really the only main draw of the job. There are several other perks, but thats the main one.
Scholar i would however siggest unlocking as SOON as you hit level 30. This will pretty much be your Sub of choice.
You "can" go as whm/Blm from 1-75, however you'l severly be gimping your potential and party invites since Whm/Sch is that much better.
As for is Whm Still needed? Yes, Whm is Always needed. We get cures the earliest, we get haste, we get AoE protects and shells and the highest tiers of these, we are also the only job who can teleport and use raise 3.
The Climb to 75 may be a bit slower since the introduction of Sch, but Whm is Still a very needed job.
Post what level and what nation you started in, so we can focus some advice for you.
In the mean time, Gl and Enjoy~
Chocobo Status: Retired Green, Black, Red, Yellow
Whm/Blm/Rdm/Mnk/Thf/Pld/Blu/Smn/Dnc/Pup/Bst/Drg 99, War 91, Brd/Sch/Sam/Nin/Cor/Drk/Rng 60, Geo 15, Run 10
Alch 72+1, Cook 66, CC 61+1, Wood 61, Synergy 56, Bone 54, Leather 51, Gold 49, Smithing 45, Fish 15 http://ffxi.allakhazam.com/profile.xml?143946