The form -(으)ㄹ래요 is a more casual version for expressing your decision or intent; or for asking for someone’s preference or intention. The first is always a statement, while the latter is always in the form of a question. So you shouldn’t have too much trouble distinguishing between the two uses of this form.
The form -(으)ㄹ래요 has, as already mentioned, two uses. You can use it to express your decision or intent to someone. Or, you can use it to ask someone for either his preference, opinion or plans. This form, however, is something to be reserved for close friends and family as the form is inherently casual for the form lacks a feeling of politeness. Furthermore, you use the form in spoken language primarily. Lastly, the form -(으)ㄹ래요 can be used in the answer to a question using the form -(으)ㄹ래요.
가: 저는 김치찌개를 먹을래요. 왕리 씨는 뭐 먹을래요?
나: 순두부찌개를 먹을래요.
A: I’ll have the kimchijjigae. What will you have, Wangli?
B: I will take the sundubujjigae.
How To Use
The form -(으)ㄹ래요 is not difficult to use. You already know the basics of its conjugation rules as you have done so for forms like -(으)ㄹ게요 and -(으)ㄹ까요. The basics are for this one the ‘batchim/no batchim’ rule, with the caveat that verbs with a ㄹ batchim are treated as having no batchim. And, you just need to keep the irregular verbs in mind. Besides, those things there is little else to tell you about the conjugation with the form -(으)ㄹ래요.
Keep in mind that -(으)ㄹ래요 used in a question is for asking after someone’s opinion, intent or plans while using it in a statement is to express your intention, plan or decision. Furthermore, when you use it for stating your plans, intents or decisions, the subject can only be the first person.